features and possible mechanisms of long range d retention in pfm’s
DESCRIPTION
Features and possible mechanisms of long range D retention in PFM’s (based on investigations carried out in RF). Presented by Valery Kurnaev. ITPA DIV SOL meeting 7-10 May 2007, Garching, Germany. 7-10 May 2007. Contributions presented by:. - PowerPoint PPT PresentationTRANSCRIPT
1
Features and possible mechanisms of long range D
retention in PFMrsquos(based on investigations carried out in RF)
Presented by
Valery Kurnaev
7-10 May 2007
ITPA DIV SOL meeting 7-10 May 2007 Garching Germany
2
Contributions presented by
bull YuMartynenko BNKolbasov AASkovoroda ASpitsin Kurchatov Research Centre
bull AAirapetov LBegrambekov AGolubeva OFadina APisarev PShigin MEPhI
bull VAlimov Institute of Physical Chemistry RAS
3
The evidence of long range D retention
Polycrystalline amp mixed materials
Long range effect at ion implantation was seen more than 40 years ago MGuseva
6 keV D is captured in the hot rolled W at depth of several microns In single crystal W D ins not captured in the bulk VAlimov et al in Hydrogen and helium recycling at PFC ed by AHassanein Kluwer Academic Publishers 2002 p131-143
In the CVD coatings of W2C and WC exposed to the D plasma at Tgt 400 K D atoms diffuse into the bulk and accumulate to 2 at at depths of several micrometers VAlimov
Carbon based materials
Deep penetration of deuterium into carbon fibre composite CF222 (up to 2-3 mm) after exposure to the PISCES-A plasma- B Emmoth M Rubel E Franconi Nucl Fusion 30 (1990) 1140
Tritium depth profiles in divertor tiles of JET have revealed that in the 2D (two-dimensional) CFC tiles about 40 of tritium was retained at depths larger than 1 mm to only few percent found at these depths in the 4D CFC tile from TFTR R-D Penzhorn N Bekris U Berndt JP Coad H Ziegler W Naumlgele J Nucl Mater 288 (2001) 170 R-D Penzhorn JP Coad N Bekris L Doerr M Friedrich W Pilz Fus Eng Des 56amp57 (2001) 105 N Bekris CH Skinner U Berndt CA Gentile M Glugla B Schweigel J Nucl Mater 313-316 (2003) 501
4
Surer deep hydrogen penetration in vanadium alloy
Hydrogen isotopes penetrate through the 07 mm sample of V-349Ga alloy to the non irradiated backside after stationary pulsed power plasma and 6-keV ions irradiation
0 50 100 1500
5
10
15
20
2
1
Con
cent
rati
on a
t
Depth nm
Hydrogen concentration profiles in V-349Ga alloy after exposition in stationary plasmaof PLAST installation (D= 2∙1025 m-2 Т = 4500С Е = 100 eV)
1 ndash irradiated side 2 - backside
(ERDA 2-MeV He+)
Preprint 64527 Kurchatov Institute
5
0 50 100 1500
1
2
3
2
1
Depth nm
Con
cent
rati
on a
t
Deuterium concentration profiles in V-349Ga alloy after irradiation with pulsed deuterium plasma (15 pulses 028 MJm2) 1 ndash backside 2 ndash irradiated side 3- non irradiated(ERDA 2-MeV He+)
0 50 100 1500
5
10
15
3
2
1
Con
cent
rati
on a
t
Depth nm
Hydrogen concentration profiles in V-349Ga alloy after irradiation with 6-keV H+ ions in ion accelerator ILU at dose 10 1023 м-2 and target temperature Т = 4500С 1 ndash irradiated side 2 - backside 3 ndash non irradiates sample(ERDA 2-MeV He+)
Surer deep hydrogen penetration in vanadium alloy (2)
6
0
200
400c
0
200
400b
Depth m
0
200
400а
Mic
roh
ard
nes
s k
gm
m2
0 100 200 300 400 100 0
Microhardness as a function of depth measured on samples cross section after stationary plasma irradiation ( ndash irradiated side - back side - before irradiation) а) V-10Ti-6Cr-005Zr ndash irradiation time 20 min (D= 22 1024 m-2)b) V-10Ti-6Cr-005Zr ndash irradiation time 1 hour (D= 64 1024 m-2) c) V-15Ti-10Cr-005Y - irradiation time 1 hour (D= 64 1024 m-2)
Hydrogen irradiation induceddeep strengthening
Stationary pulsed power hydrogen plasma and 6-keV H+ ions irradiation results in deep strengthening ndash a reason is hydrates formation which create compressive stress in material
Preprint 64527 Kurchatov Institute
Before irradiation
backside
7
0 1 2 3 4 510-2
10-1
100
101
0 1 2 3 4 510-2
10-1
100
101
a)
W2C + 10 at C
200 eV D plasma CVD coatings 2x1024 Dm2
D c
on
ce
ntr
atio
n [a
t
]
Texp
= 373 K T
exp = 433 K
Texp
= 503 K
b)
WC + 10 at C
Texp
= 413 K T
exp = 543 K
Texp
= 653 K T
exp = 813 K
D c
on
ce
ntr
atio
n [a
t
]
Depth [m]
NRA analysis of CVD W2C amp WC coatings (VAlimov et al)
At temperatures above 550 K D concentration in the bulk starts to decrease
Presumably deuterium is retained in carbon precipitates
8
Mechanisms of long range D transportYuMartynenko et al
Shock wave initiation
ion
Cascade of displacements
defects
Physical interpretation connected with generation and transport of dislocation loops under influence of surface layer tension generation of thermoelastic tension and shock waves that force diffusion of admixtures along interstitials and grain borders
9
But physical mechanisms are far from full understanding
For adequate explanation versatile investigations using novel experimental methods as well as intimate theoretical analysis are necessary
For chemical active C based materials with compound structure (CFC) the task is much more complicated and need very careful investigations
10
0 2 4 6 8 1010-3
10-2
10-1
100
101 200 eV D plasma CFC NB31 2x1024 Dm2
Texp
= 463 K T
exp = 673 K
Texp
= 773 K T
exp = 948 K
D c
once
ntra
tion
[at
]
Depth [m]
0( ) [1 erf( )]2
xC x C
Dt
Migration in the bulk obeys diffusion equation with D=D(Fluence Temp)
10 15 20 25 3010-17
10-15
10-13
10-11
10-9
10-7
NB31 200 eV D plasma (Magnetron)
Coe
ffici
ent o
f D m
igra
tion
[m2 s
]
1000Temperature [K-1]
LA Sedano et al (1998) NB11 Matrix N11 Matrix NB11 Fibres N11 Fibres
Values for the deuterium migration derived from the D depth profiles are in good agreement with data for intrinsic hydrogen diffusivity in the fibres Migration through pores along fibres with low activation energy may be considered as mechanism of deuterium penetration into the bulk of the CFC materials
Channels of D transport in CFC VAlimov et al
11
Fine grain graphite (as well as CFC) ndashtransparent for gases in principle
Penetrating gas flow via gas pressure for MPG-8 graphite (thickness 126 mm diameter 305 mm)
room temperature
Measured gas flux density j ~ σ P σ Ad
P ndashpressure A ndasharea d- thickness σ ndash specific gas permeability
σ = 5middot1015 mols for MPG-8
Flu
x m
ols
Pressure Pa
Graphite sheet behaves as capillary A=1m2 d =1cm P =1Pa 35middot1017 D2s
12
Influence of tokamak T-10 exposure on MPG-8 graphite permeability
MPG-8 membrane 18 mm thick cut off T-10 limiter demonstrated hydrogen permeability ~9middot1015 molmiddotc-1m-1Pa-1 - 2 times more than for ldquovirginrdquo graphite
Possible reason ndash graphite porosity increase after long term expose in tokamak
All attempts to increase MPG-8 permeability in lab plasma experiments failed
4 mm
Place of limiter tile used for the membrane
14
Comparison of lab experiments and tokamak exposed tile retention in CFC
TDS investigation of the samples CFC N11 implanted by deuterium ions in the laboratory setups (MEPhI) and high field side tile of Tore Supra
[1] Begrambekov L Brosset C Bucalossi J Delchambre E Gunn JP Grisolia C Lipa M Loarer T Mitteau R PMoner-Garbet P Pascal J-Y PShigin P Titov N Tsitrone E Vergazov S Zakharov A ldquoSurface modification and hydrogen isotope retention in CFC during plasma irradiation in the Tore Supra tokamakrdquo17th Internal Conference on Plasma Surface Interactions in Controlled Fusion Devices (PSI17) Hefei China May 22 ndash 26 2006
LABORATORY SAMPLE
TORE SUPRA TILE [1]
Particles deuterons deuterons
Ion energy 50 100 200
500 eV
10-100 eV (as well as low energy atoms molecules and charge exchange neutrals )
Ion flux density 1times1020 atm2s (1-2)times1019 atm2s
Fluence 5times1023 atm2 5times1023 atm2 (estimated)
Surface temperature 450-470 K up to 500-600 K
Retention ~07times1021 atm2 ~2times1022 atm2 (30 times higher)
15
Hydrogen retention via fluence in lab exp
1021 1022 1023 1024 10251020
1021
1022
Hyd
roge
n re
tent
ion
at
m2
Fluence atm2
B4C 100 eVH MPG-8 100 eVH MPG-8 1 keVH HPG99 1 keVH [1] HOPG 100 eVH HOPG 1 keVH
Ion flux density = 35x1020 at(secm2)
[2] L Begrambekov O Buzhinsky A Gordeev E Miljaeva P Leikin P Shigin TDS investigation of hydrogen retention in graphites and carbon based materials Physica scripta N108 (2004) p72-75
Possible underestimation of tokamak tile irradiation fluence hardly could seriously influence the presented data -hydrogen retention will not increase 30 times even for ~100 times higher fluence
16
Possible mechanisms of enhanced D
trapping under tokamak plasma irradiation
1 Presence of hydrogen in the Tore Supra tiles
TDS spectra of H2 and D2 for the as prepared CFC N11 samples irradiated in deuterium plasma
Ei = 100 eVat
Ji = 121020 atm2s
Ф = 451023 atm2
Presence of hydrogen in the CFC twice increases deuterium trapping at the expense of filling the hydrogen traps by deuterium due to isotope
exchange mechanism
Lab experiment
17
2 Trapping of deuterium activated by electron irradiation
[ Collaboration DRFC CEA-Cadarache ndash MEPhI ROSATOM 2007]
Thermal desorption of deuterium as D2
and as CD4 from CFC graphite under
ion and electron irradiationEi=100 eVat Ji=121020 atm2s
Ф=451023 atm2
Increase of deuterium retention along with irradiation time as well as deuterium retention under electron irradiation support an assumption about participation of D2
molecules from surrounding atmosphere in deuterium trapping into graphites Ion and electron irradiation act as a driving forces of the process
Plasma electron irradiation of CFC increased deuterium trapping 12 ndash 3 times depending on energy distribution of impinging deuterium particles
0 200 400 600 800 100000
05
10
15
Ret
entio
n x
1017
at
cm2
Energy eVat
CFC D2 (1020)
D2 electron irr
CFC D2 (2x1019)
electronirradiation
18
3 Transportation of deuterium into the material and trapping in the bulk of the tile
TDS analysis of the samples cut from different depth of the tile shows that more 10 of cumulative trapping collected in the bulk of tile
The samples of 1 ndash 2 mm thickness are usually used in the laboratory experiments The laboratory results could be compared
only to trapping in surface region of tokamak tile
4 Deuterium trapping in graphites irradiated by ion flux with wide energy distribution
Peculiarities of deuterium trapping in graphites exposed to plasma allows to expect an enhancement of retention in graphites irradiated by ion flux with wide energy distribution in tokamaks in comparison with graphites subjected to mono energy ion irradiation in laboratory
setups
19
5 Graphite surface irradiation during Helium Glow Discharge Conditioning
Helium ion bombardment leads to development of the surface relief and destruction of near surface layer As result trapping of deuterium during tokamak discharges should be enhanced
6 Graphite surface irradiation by oxygen impurities
Graphite irradiation by ions and atoms of oxygen impurities leads to accelerated surface destruction and develop the surface As a result trapping of deuterium ions and neutrals by graphite surface is probably more enhanced
20
Conclusion
bull The long range D retention in general is the very complicated physical (amp chemical) problem Many observed features of this phenomenon is not clear now
bull Complex and multiple-factor impact of PFM in tokamaks makes difficult distinguishing its influence on the LR hydrogen isotopes retention
bull Laboratory experiments with well defined impact parameters are crucially necessary
bull During last two years we mounted and calibrated a series of high vacuum installations with well controlled parameters for measurement of D retention in plasma exposed (as well in situ in simulators) samples and started comparative studies of samples radiated at different tokamaks and laboratory installations
21
Plansbull Investigations of samples irradiated in LENTA PR-2
PIN laboratory plasma facilities as well as in T-10 TEXTOR and Tore Supra tokamaks are now in progress
bull As there is very large scattering of the experimental data
on D retention careful measurements at D retention via fluxes (at high fluxes) and temperature in different irradiation facilities are under way
bull To pick up contribution of different factors on D retention step by step experimental investigations at varying definite factors (im flux density consequent and simultaneous irradiation with deuterium and helium broad energy spectra influence etc) are planned
bull Experimental measurements of neutron irradiation influence on hydrogen isotopes retention in PFM is now discussed
- Slide 1
- Slide 2
- Slide 3
- Slide 4
- Slide 5
- Slide 6
- Slide 7
- Slide 8
- Slide 9
- Slide 10
- Slide 11
- Slide 12
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- Slide 21
-
2
Contributions presented by
bull YuMartynenko BNKolbasov AASkovoroda ASpitsin Kurchatov Research Centre
bull AAirapetov LBegrambekov AGolubeva OFadina APisarev PShigin MEPhI
bull VAlimov Institute of Physical Chemistry RAS
3
The evidence of long range D retention
Polycrystalline amp mixed materials
Long range effect at ion implantation was seen more than 40 years ago MGuseva
6 keV D is captured in the hot rolled W at depth of several microns In single crystal W D ins not captured in the bulk VAlimov et al in Hydrogen and helium recycling at PFC ed by AHassanein Kluwer Academic Publishers 2002 p131-143
In the CVD coatings of W2C and WC exposed to the D plasma at Tgt 400 K D atoms diffuse into the bulk and accumulate to 2 at at depths of several micrometers VAlimov
Carbon based materials
Deep penetration of deuterium into carbon fibre composite CF222 (up to 2-3 mm) after exposure to the PISCES-A plasma- B Emmoth M Rubel E Franconi Nucl Fusion 30 (1990) 1140
Tritium depth profiles in divertor tiles of JET have revealed that in the 2D (two-dimensional) CFC tiles about 40 of tritium was retained at depths larger than 1 mm to only few percent found at these depths in the 4D CFC tile from TFTR R-D Penzhorn N Bekris U Berndt JP Coad H Ziegler W Naumlgele J Nucl Mater 288 (2001) 170 R-D Penzhorn JP Coad N Bekris L Doerr M Friedrich W Pilz Fus Eng Des 56amp57 (2001) 105 N Bekris CH Skinner U Berndt CA Gentile M Glugla B Schweigel J Nucl Mater 313-316 (2003) 501
4
Surer deep hydrogen penetration in vanadium alloy
Hydrogen isotopes penetrate through the 07 mm sample of V-349Ga alloy to the non irradiated backside after stationary pulsed power plasma and 6-keV ions irradiation
0 50 100 1500
5
10
15
20
2
1
Con
cent
rati
on a
t
Depth nm
Hydrogen concentration profiles in V-349Ga alloy after exposition in stationary plasmaof PLAST installation (D= 2∙1025 m-2 Т = 4500С Е = 100 eV)
1 ndash irradiated side 2 - backside
(ERDA 2-MeV He+)
Preprint 64527 Kurchatov Institute
5
0 50 100 1500
1
2
3
2
1
Depth nm
Con
cent
rati
on a
t
Deuterium concentration profiles in V-349Ga alloy after irradiation with pulsed deuterium plasma (15 pulses 028 MJm2) 1 ndash backside 2 ndash irradiated side 3- non irradiated(ERDA 2-MeV He+)
0 50 100 1500
5
10
15
3
2
1
Con
cent
rati
on a
t
Depth nm
Hydrogen concentration profiles in V-349Ga alloy after irradiation with 6-keV H+ ions in ion accelerator ILU at dose 10 1023 м-2 and target temperature Т = 4500С 1 ndash irradiated side 2 - backside 3 ndash non irradiates sample(ERDA 2-MeV He+)
Surer deep hydrogen penetration in vanadium alloy (2)
6
0
200
400c
0
200
400b
Depth m
0
200
400а
Mic
roh
ard
nes
s k
gm
m2
0 100 200 300 400 100 0
Microhardness as a function of depth measured on samples cross section after stationary plasma irradiation ( ndash irradiated side - back side - before irradiation) а) V-10Ti-6Cr-005Zr ndash irradiation time 20 min (D= 22 1024 m-2)b) V-10Ti-6Cr-005Zr ndash irradiation time 1 hour (D= 64 1024 m-2) c) V-15Ti-10Cr-005Y - irradiation time 1 hour (D= 64 1024 m-2)
Hydrogen irradiation induceddeep strengthening
Stationary pulsed power hydrogen plasma and 6-keV H+ ions irradiation results in deep strengthening ndash a reason is hydrates formation which create compressive stress in material
Preprint 64527 Kurchatov Institute
Before irradiation
backside
7
0 1 2 3 4 510-2
10-1
100
101
0 1 2 3 4 510-2
10-1
100
101
a)
W2C + 10 at C
200 eV D plasma CVD coatings 2x1024 Dm2
D c
on
ce
ntr
atio
n [a
t
]
Texp
= 373 K T
exp = 433 K
Texp
= 503 K
b)
WC + 10 at C
Texp
= 413 K T
exp = 543 K
Texp
= 653 K T
exp = 813 K
D c
on
ce
ntr
atio
n [a
t
]
Depth [m]
NRA analysis of CVD W2C amp WC coatings (VAlimov et al)
At temperatures above 550 K D concentration in the bulk starts to decrease
Presumably deuterium is retained in carbon precipitates
8
Mechanisms of long range D transportYuMartynenko et al
Shock wave initiation
ion
Cascade of displacements
defects
Physical interpretation connected with generation and transport of dislocation loops under influence of surface layer tension generation of thermoelastic tension and shock waves that force diffusion of admixtures along interstitials and grain borders
9
But physical mechanisms are far from full understanding
For adequate explanation versatile investigations using novel experimental methods as well as intimate theoretical analysis are necessary
For chemical active C based materials with compound structure (CFC) the task is much more complicated and need very careful investigations
10
0 2 4 6 8 1010-3
10-2
10-1
100
101 200 eV D plasma CFC NB31 2x1024 Dm2
Texp
= 463 K T
exp = 673 K
Texp
= 773 K T
exp = 948 K
D c
once
ntra
tion
[at
]
Depth [m]
0( ) [1 erf( )]2
xC x C
Dt
Migration in the bulk obeys diffusion equation with D=D(Fluence Temp)
10 15 20 25 3010-17
10-15
10-13
10-11
10-9
10-7
NB31 200 eV D plasma (Magnetron)
Coe
ffici
ent o
f D m
igra
tion
[m2 s
]
1000Temperature [K-1]
LA Sedano et al (1998) NB11 Matrix N11 Matrix NB11 Fibres N11 Fibres
Values for the deuterium migration derived from the D depth profiles are in good agreement with data for intrinsic hydrogen diffusivity in the fibres Migration through pores along fibres with low activation energy may be considered as mechanism of deuterium penetration into the bulk of the CFC materials
Channels of D transport in CFC VAlimov et al
11
Fine grain graphite (as well as CFC) ndashtransparent for gases in principle
Penetrating gas flow via gas pressure for MPG-8 graphite (thickness 126 mm diameter 305 mm)
room temperature
Measured gas flux density j ~ σ P σ Ad
P ndashpressure A ndasharea d- thickness σ ndash specific gas permeability
σ = 5middot1015 mols for MPG-8
Flu
x m
ols
Pressure Pa
Graphite sheet behaves as capillary A=1m2 d =1cm P =1Pa 35middot1017 D2s
12
Influence of tokamak T-10 exposure on MPG-8 graphite permeability
MPG-8 membrane 18 mm thick cut off T-10 limiter demonstrated hydrogen permeability ~9middot1015 molmiddotc-1m-1Pa-1 - 2 times more than for ldquovirginrdquo graphite
Possible reason ndash graphite porosity increase after long term expose in tokamak
All attempts to increase MPG-8 permeability in lab plasma experiments failed
4 mm
Place of limiter tile used for the membrane
14
Comparison of lab experiments and tokamak exposed tile retention in CFC
TDS investigation of the samples CFC N11 implanted by deuterium ions in the laboratory setups (MEPhI) and high field side tile of Tore Supra
[1] Begrambekov L Brosset C Bucalossi J Delchambre E Gunn JP Grisolia C Lipa M Loarer T Mitteau R PMoner-Garbet P Pascal J-Y PShigin P Titov N Tsitrone E Vergazov S Zakharov A ldquoSurface modification and hydrogen isotope retention in CFC during plasma irradiation in the Tore Supra tokamakrdquo17th Internal Conference on Plasma Surface Interactions in Controlled Fusion Devices (PSI17) Hefei China May 22 ndash 26 2006
LABORATORY SAMPLE
TORE SUPRA TILE [1]
Particles deuterons deuterons
Ion energy 50 100 200
500 eV
10-100 eV (as well as low energy atoms molecules and charge exchange neutrals )
Ion flux density 1times1020 atm2s (1-2)times1019 atm2s
Fluence 5times1023 atm2 5times1023 atm2 (estimated)
Surface temperature 450-470 K up to 500-600 K
Retention ~07times1021 atm2 ~2times1022 atm2 (30 times higher)
15
Hydrogen retention via fluence in lab exp
1021 1022 1023 1024 10251020
1021
1022
Hyd
roge
n re
tent
ion
at
m2
Fluence atm2
B4C 100 eVH MPG-8 100 eVH MPG-8 1 keVH HPG99 1 keVH [1] HOPG 100 eVH HOPG 1 keVH
Ion flux density = 35x1020 at(secm2)
[2] L Begrambekov O Buzhinsky A Gordeev E Miljaeva P Leikin P Shigin TDS investigation of hydrogen retention in graphites and carbon based materials Physica scripta N108 (2004) p72-75
Possible underestimation of tokamak tile irradiation fluence hardly could seriously influence the presented data -hydrogen retention will not increase 30 times even for ~100 times higher fluence
16
Possible mechanisms of enhanced D
trapping under tokamak plasma irradiation
1 Presence of hydrogen in the Tore Supra tiles
TDS spectra of H2 and D2 for the as prepared CFC N11 samples irradiated in deuterium plasma
Ei = 100 eVat
Ji = 121020 atm2s
Ф = 451023 atm2
Presence of hydrogen in the CFC twice increases deuterium trapping at the expense of filling the hydrogen traps by deuterium due to isotope
exchange mechanism
Lab experiment
17
2 Trapping of deuterium activated by electron irradiation
[ Collaboration DRFC CEA-Cadarache ndash MEPhI ROSATOM 2007]
Thermal desorption of deuterium as D2
and as CD4 from CFC graphite under
ion and electron irradiationEi=100 eVat Ji=121020 atm2s
Ф=451023 atm2
Increase of deuterium retention along with irradiation time as well as deuterium retention under electron irradiation support an assumption about participation of D2
molecules from surrounding atmosphere in deuterium trapping into graphites Ion and electron irradiation act as a driving forces of the process
Plasma electron irradiation of CFC increased deuterium trapping 12 ndash 3 times depending on energy distribution of impinging deuterium particles
0 200 400 600 800 100000
05
10
15
Ret
entio
n x
1017
at
cm2
Energy eVat
CFC D2 (1020)
D2 electron irr
CFC D2 (2x1019)
electronirradiation
18
3 Transportation of deuterium into the material and trapping in the bulk of the tile
TDS analysis of the samples cut from different depth of the tile shows that more 10 of cumulative trapping collected in the bulk of tile
The samples of 1 ndash 2 mm thickness are usually used in the laboratory experiments The laboratory results could be compared
only to trapping in surface region of tokamak tile
4 Deuterium trapping in graphites irradiated by ion flux with wide energy distribution
Peculiarities of deuterium trapping in graphites exposed to plasma allows to expect an enhancement of retention in graphites irradiated by ion flux with wide energy distribution in tokamaks in comparison with graphites subjected to mono energy ion irradiation in laboratory
setups
19
5 Graphite surface irradiation during Helium Glow Discharge Conditioning
Helium ion bombardment leads to development of the surface relief and destruction of near surface layer As result trapping of deuterium during tokamak discharges should be enhanced
6 Graphite surface irradiation by oxygen impurities
Graphite irradiation by ions and atoms of oxygen impurities leads to accelerated surface destruction and develop the surface As a result trapping of deuterium ions and neutrals by graphite surface is probably more enhanced
20
Conclusion
bull The long range D retention in general is the very complicated physical (amp chemical) problem Many observed features of this phenomenon is not clear now
bull Complex and multiple-factor impact of PFM in tokamaks makes difficult distinguishing its influence on the LR hydrogen isotopes retention
bull Laboratory experiments with well defined impact parameters are crucially necessary
bull During last two years we mounted and calibrated a series of high vacuum installations with well controlled parameters for measurement of D retention in plasma exposed (as well in situ in simulators) samples and started comparative studies of samples radiated at different tokamaks and laboratory installations
21
Plansbull Investigations of samples irradiated in LENTA PR-2
PIN laboratory plasma facilities as well as in T-10 TEXTOR and Tore Supra tokamaks are now in progress
bull As there is very large scattering of the experimental data
on D retention careful measurements at D retention via fluxes (at high fluxes) and temperature in different irradiation facilities are under way
bull To pick up contribution of different factors on D retention step by step experimental investigations at varying definite factors (im flux density consequent and simultaneous irradiation with deuterium and helium broad energy spectra influence etc) are planned
bull Experimental measurements of neutron irradiation influence on hydrogen isotopes retention in PFM is now discussed
- Slide 1
- Slide 2
- Slide 3
- Slide 4
- Slide 5
- Slide 6
- Slide 7
- Slide 8
- Slide 9
- Slide 10
- Slide 11
- Slide 12
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- Slide 21
-
3
The evidence of long range D retention
Polycrystalline amp mixed materials
Long range effect at ion implantation was seen more than 40 years ago MGuseva
6 keV D is captured in the hot rolled W at depth of several microns In single crystal W D ins not captured in the bulk VAlimov et al in Hydrogen and helium recycling at PFC ed by AHassanein Kluwer Academic Publishers 2002 p131-143
In the CVD coatings of W2C and WC exposed to the D plasma at Tgt 400 K D atoms diffuse into the bulk and accumulate to 2 at at depths of several micrometers VAlimov
Carbon based materials
Deep penetration of deuterium into carbon fibre composite CF222 (up to 2-3 mm) after exposure to the PISCES-A plasma- B Emmoth M Rubel E Franconi Nucl Fusion 30 (1990) 1140
Tritium depth profiles in divertor tiles of JET have revealed that in the 2D (two-dimensional) CFC tiles about 40 of tritium was retained at depths larger than 1 mm to only few percent found at these depths in the 4D CFC tile from TFTR R-D Penzhorn N Bekris U Berndt JP Coad H Ziegler W Naumlgele J Nucl Mater 288 (2001) 170 R-D Penzhorn JP Coad N Bekris L Doerr M Friedrich W Pilz Fus Eng Des 56amp57 (2001) 105 N Bekris CH Skinner U Berndt CA Gentile M Glugla B Schweigel J Nucl Mater 313-316 (2003) 501
4
Surer deep hydrogen penetration in vanadium alloy
Hydrogen isotopes penetrate through the 07 mm sample of V-349Ga alloy to the non irradiated backside after stationary pulsed power plasma and 6-keV ions irradiation
0 50 100 1500
5
10
15
20
2
1
Con
cent
rati
on a
t
Depth nm
Hydrogen concentration profiles in V-349Ga alloy after exposition in stationary plasmaof PLAST installation (D= 2∙1025 m-2 Т = 4500С Е = 100 eV)
1 ndash irradiated side 2 - backside
(ERDA 2-MeV He+)
Preprint 64527 Kurchatov Institute
5
0 50 100 1500
1
2
3
2
1
Depth nm
Con
cent
rati
on a
t
Deuterium concentration profiles in V-349Ga alloy after irradiation with pulsed deuterium plasma (15 pulses 028 MJm2) 1 ndash backside 2 ndash irradiated side 3- non irradiated(ERDA 2-MeV He+)
0 50 100 1500
5
10
15
3
2
1
Con
cent
rati
on a
t
Depth nm
Hydrogen concentration profiles in V-349Ga alloy after irradiation with 6-keV H+ ions in ion accelerator ILU at dose 10 1023 м-2 and target temperature Т = 4500С 1 ndash irradiated side 2 - backside 3 ndash non irradiates sample(ERDA 2-MeV He+)
Surer deep hydrogen penetration in vanadium alloy (2)
6
0
200
400c
0
200
400b
Depth m
0
200
400а
Mic
roh
ard
nes
s k
gm
m2
0 100 200 300 400 100 0
Microhardness as a function of depth measured on samples cross section after stationary plasma irradiation ( ndash irradiated side - back side - before irradiation) а) V-10Ti-6Cr-005Zr ndash irradiation time 20 min (D= 22 1024 m-2)b) V-10Ti-6Cr-005Zr ndash irradiation time 1 hour (D= 64 1024 m-2) c) V-15Ti-10Cr-005Y - irradiation time 1 hour (D= 64 1024 m-2)
Hydrogen irradiation induceddeep strengthening
Stationary pulsed power hydrogen plasma and 6-keV H+ ions irradiation results in deep strengthening ndash a reason is hydrates formation which create compressive stress in material
Preprint 64527 Kurchatov Institute
Before irradiation
backside
7
0 1 2 3 4 510-2
10-1
100
101
0 1 2 3 4 510-2
10-1
100
101
a)
W2C + 10 at C
200 eV D plasma CVD coatings 2x1024 Dm2
D c
on
ce
ntr
atio
n [a
t
]
Texp
= 373 K T
exp = 433 K
Texp
= 503 K
b)
WC + 10 at C
Texp
= 413 K T
exp = 543 K
Texp
= 653 K T
exp = 813 K
D c
on
ce
ntr
atio
n [a
t
]
Depth [m]
NRA analysis of CVD W2C amp WC coatings (VAlimov et al)
At temperatures above 550 K D concentration in the bulk starts to decrease
Presumably deuterium is retained in carbon precipitates
8
Mechanisms of long range D transportYuMartynenko et al
Shock wave initiation
ion
Cascade of displacements
defects
Physical interpretation connected with generation and transport of dislocation loops under influence of surface layer tension generation of thermoelastic tension and shock waves that force diffusion of admixtures along interstitials and grain borders
9
But physical mechanisms are far from full understanding
For adequate explanation versatile investigations using novel experimental methods as well as intimate theoretical analysis are necessary
For chemical active C based materials with compound structure (CFC) the task is much more complicated and need very careful investigations
10
0 2 4 6 8 1010-3
10-2
10-1
100
101 200 eV D plasma CFC NB31 2x1024 Dm2
Texp
= 463 K T
exp = 673 K
Texp
= 773 K T
exp = 948 K
D c
once
ntra
tion
[at
]
Depth [m]
0( ) [1 erf( )]2
xC x C
Dt
Migration in the bulk obeys diffusion equation with D=D(Fluence Temp)
10 15 20 25 3010-17
10-15
10-13
10-11
10-9
10-7
NB31 200 eV D plasma (Magnetron)
Coe
ffici
ent o
f D m
igra
tion
[m2 s
]
1000Temperature [K-1]
LA Sedano et al (1998) NB11 Matrix N11 Matrix NB11 Fibres N11 Fibres
Values for the deuterium migration derived from the D depth profiles are in good agreement with data for intrinsic hydrogen diffusivity in the fibres Migration through pores along fibres with low activation energy may be considered as mechanism of deuterium penetration into the bulk of the CFC materials
Channels of D transport in CFC VAlimov et al
11
Fine grain graphite (as well as CFC) ndashtransparent for gases in principle
Penetrating gas flow via gas pressure for MPG-8 graphite (thickness 126 mm diameter 305 mm)
room temperature
Measured gas flux density j ~ σ P σ Ad
P ndashpressure A ndasharea d- thickness σ ndash specific gas permeability
σ = 5middot1015 mols for MPG-8
Flu
x m
ols
Pressure Pa
Graphite sheet behaves as capillary A=1m2 d =1cm P =1Pa 35middot1017 D2s
12
Influence of tokamak T-10 exposure on MPG-8 graphite permeability
MPG-8 membrane 18 mm thick cut off T-10 limiter demonstrated hydrogen permeability ~9middot1015 molmiddotc-1m-1Pa-1 - 2 times more than for ldquovirginrdquo graphite
Possible reason ndash graphite porosity increase after long term expose in tokamak
All attempts to increase MPG-8 permeability in lab plasma experiments failed
4 mm
Place of limiter tile used for the membrane
14
Comparison of lab experiments and tokamak exposed tile retention in CFC
TDS investigation of the samples CFC N11 implanted by deuterium ions in the laboratory setups (MEPhI) and high field side tile of Tore Supra
[1] Begrambekov L Brosset C Bucalossi J Delchambre E Gunn JP Grisolia C Lipa M Loarer T Mitteau R PMoner-Garbet P Pascal J-Y PShigin P Titov N Tsitrone E Vergazov S Zakharov A ldquoSurface modification and hydrogen isotope retention in CFC during plasma irradiation in the Tore Supra tokamakrdquo17th Internal Conference on Plasma Surface Interactions in Controlled Fusion Devices (PSI17) Hefei China May 22 ndash 26 2006
LABORATORY SAMPLE
TORE SUPRA TILE [1]
Particles deuterons deuterons
Ion energy 50 100 200
500 eV
10-100 eV (as well as low energy atoms molecules and charge exchange neutrals )
Ion flux density 1times1020 atm2s (1-2)times1019 atm2s
Fluence 5times1023 atm2 5times1023 atm2 (estimated)
Surface temperature 450-470 K up to 500-600 K
Retention ~07times1021 atm2 ~2times1022 atm2 (30 times higher)
15
Hydrogen retention via fluence in lab exp
1021 1022 1023 1024 10251020
1021
1022
Hyd
roge
n re
tent
ion
at
m2
Fluence atm2
B4C 100 eVH MPG-8 100 eVH MPG-8 1 keVH HPG99 1 keVH [1] HOPG 100 eVH HOPG 1 keVH
Ion flux density = 35x1020 at(secm2)
[2] L Begrambekov O Buzhinsky A Gordeev E Miljaeva P Leikin P Shigin TDS investigation of hydrogen retention in graphites and carbon based materials Physica scripta N108 (2004) p72-75
Possible underestimation of tokamak tile irradiation fluence hardly could seriously influence the presented data -hydrogen retention will not increase 30 times even for ~100 times higher fluence
16
Possible mechanisms of enhanced D
trapping under tokamak plasma irradiation
1 Presence of hydrogen in the Tore Supra tiles
TDS spectra of H2 and D2 for the as prepared CFC N11 samples irradiated in deuterium plasma
Ei = 100 eVat
Ji = 121020 atm2s
Ф = 451023 atm2
Presence of hydrogen in the CFC twice increases deuterium trapping at the expense of filling the hydrogen traps by deuterium due to isotope
exchange mechanism
Lab experiment
17
2 Trapping of deuterium activated by electron irradiation
[ Collaboration DRFC CEA-Cadarache ndash MEPhI ROSATOM 2007]
Thermal desorption of deuterium as D2
and as CD4 from CFC graphite under
ion and electron irradiationEi=100 eVat Ji=121020 atm2s
Ф=451023 atm2
Increase of deuterium retention along with irradiation time as well as deuterium retention under electron irradiation support an assumption about participation of D2
molecules from surrounding atmosphere in deuterium trapping into graphites Ion and electron irradiation act as a driving forces of the process
Plasma electron irradiation of CFC increased deuterium trapping 12 ndash 3 times depending on energy distribution of impinging deuterium particles
0 200 400 600 800 100000
05
10
15
Ret
entio
n x
1017
at
cm2
Energy eVat
CFC D2 (1020)
D2 electron irr
CFC D2 (2x1019)
electronirradiation
18
3 Transportation of deuterium into the material and trapping in the bulk of the tile
TDS analysis of the samples cut from different depth of the tile shows that more 10 of cumulative trapping collected in the bulk of tile
The samples of 1 ndash 2 mm thickness are usually used in the laboratory experiments The laboratory results could be compared
only to trapping in surface region of tokamak tile
4 Deuterium trapping in graphites irradiated by ion flux with wide energy distribution
Peculiarities of deuterium trapping in graphites exposed to plasma allows to expect an enhancement of retention in graphites irradiated by ion flux with wide energy distribution in tokamaks in comparison with graphites subjected to mono energy ion irradiation in laboratory
setups
19
5 Graphite surface irradiation during Helium Glow Discharge Conditioning
Helium ion bombardment leads to development of the surface relief and destruction of near surface layer As result trapping of deuterium during tokamak discharges should be enhanced
6 Graphite surface irradiation by oxygen impurities
Graphite irradiation by ions and atoms of oxygen impurities leads to accelerated surface destruction and develop the surface As a result trapping of deuterium ions and neutrals by graphite surface is probably more enhanced
20
Conclusion
bull The long range D retention in general is the very complicated physical (amp chemical) problem Many observed features of this phenomenon is not clear now
bull Complex and multiple-factor impact of PFM in tokamaks makes difficult distinguishing its influence on the LR hydrogen isotopes retention
bull Laboratory experiments with well defined impact parameters are crucially necessary
bull During last two years we mounted and calibrated a series of high vacuum installations with well controlled parameters for measurement of D retention in plasma exposed (as well in situ in simulators) samples and started comparative studies of samples radiated at different tokamaks and laboratory installations
21
Plansbull Investigations of samples irradiated in LENTA PR-2
PIN laboratory plasma facilities as well as in T-10 TEXTOR and Tore Supra tokamaks are now in progress
bull As there is very large scattering of the experimental data
on D retention careful measurements at D retention via fluxes (at high fluxes) and temperature in different irradiation facilities are under way
bull To pick up contribution of different factors on D retention step by step experimental investigations at varying definite factors (im flux density consequent and simultaneous irradiation with deuterium and helium broad energy spectra influence etc) are planned
bull Experimental measurements of neutron irradiation influence on hydrogen isotopes retention in PFM is now discussed
- Slide 1
- Slide 2
- Slide 3
- Slide 4
- Slide 5
- Slide 6
- Slide 7
- Slide 8
- Slide 9
- Slide 10
- Slide 11
- Slide 12
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- Slide 21
-
4
Surer deep hydrogen penetration in vanadium alloy
Hydrogen isotopes penetrate through the 07 mm sample of V-349Ga alloy to the non irradiated backside after stationary pulsed power plasma and 6-keV ions irradiation
0 50 100 1500
5
10
15
20
2
1
Con
cent
rati
on a
t
Depth nm
Hydrogen concentration profiles in V-349Ga alloy after exposition in stationary plasmaof PLAST installation (D= 2∙1025 m-2 Т = 4500С Е = 100 eV)
1 ndash irradiated side 2 - backside
(ERDA 2-MeV He+)
Preprint 64527 Kurchatov Institute
5
0 50 100 1500
1
2
3
2
1
Depth nm
Con
cent
rati
on a
t
Deuterium concentration profiles in V-349Ga alloy after irradiation with pulsed deuterium plasma (15 pulses 028 MJm2) 1 ndash backside 2 ndash irradiated side 3- non irradiated(ERDA 2-MeV He+)
0 50 100 1500
5
10
15
3
2
1
Con
cent
rati
on a
t
Depth nm
Hydrogen concentration profiles in V-349Ga alloy after irradiation with 6-keV H+ ions in ion accelerator ILU at dose 10 1023 м-2 and target temperature Т = 4500С 1 ndash irradiated side 2 - backside 3 ndash non irradiates sample(ERDA 2-MeV He+)
Surer deep hydrogen penetration in vanadium alloy (2)
6
0
200
400c
0
200
400b
Depth m
0
200
400а
Mic
roh
ard
nes
s k
gm
m2
0 100 200 300 400 100 0
Microhardness as a function of depth measured on samples cross section after stationary plasma irradiation ( ndash irradiated side - back side - before irradiation) а) V-10Ti-6Cr-005Zr ndash irradiation time 20 min (D= 22 1024 m-2)b) V-10Ti-6Cr-005Zr ndash irradiation time 1 hour (D= 64 1024 m-2) c) V-15Ti-10Cr-005Y - irradiation time 1 hour (D= 64 1024 m-2)
Hydrogen irradiation induceddeep strengthening
Stationary pulsed power hydrogen plasma and 6-keV H+ ions irradiation results in deep strengthening ndash a reason is hydrates formation which create compressive stress in material
Preprint 64527 Kurchatov Institute
Before irradiation
backside
7
0 1 2 3 4 510-2
10-1
100
101
0 1 2 3 4 510-2
10-1
100
101
a)
W2C + 10 at C
200 eV D plasma CVD coatings 2x1024 Dm2
D c
on
ce
ntr
atio
n [a
t
]
Texp
= 373 K T
exp = 433 K
Texp
= 503 K
b)
WC + 10 at C
Texp
= 413 K T
exp = 543 K
Texp
= 653 K T
exp = 813 K
D c
on
ce
ntr
atio
n [a
t
]
Depth [m]
NRA analysis of CVD W2C amp WC coatings (VAlimov et al)
At temperatures above 550 K D concentration in the bulk starts to decrease
Presumably deuterium is retained in carbon precipitates
8
Mechanisms of long range D transportYuMartynenko et al
Shock wave initiation
ion
Cascade of displacements
defects
Physical interpretation connected with generation and transport of dislocation loops under influence of surface layer tension generation of thermoelastic tension and shock waves that force diffusion of admixtures along interstitials and grain borders
9
But physical mechanisms are far from full understanding
For adequate explanation versatile investigations using novel experimental methods as well as intimate theoretical analysis are necessary
For chemical active C based materials with compound structure (CFC) the task is much more complicated and need very careful investigations
10
0 2 4 6 8 1010-3
10-2
10-1
100
101 200 eV D plasma CFC NB31 2x1024 Dm2
Texp
= 463 K T
exp = 673 K
Texp
= 773 K T
exp = 948 K
D c
once
ntra
tion
[at
]
Depth [m]
0( ) [1 erf( )]2
xC x C
Dt
Migration in the bulk obeys diffusion equation with D=D(Fluence Temp)
10 15 20 25 3010-17
10-15
10-13
10-11
10-9
10-7
NB31 200 eV D plasma (Magnetron)
Coe
ffici
ent o
f D m
igra
tion
[m2 s
]
1000Temperature [K-1]
LA Sedano et al (1998) NB11 Matrix N11 Matrix NB11 Fibres N11 Fibres
Values for the deuterium migration derived from the D depth profiles are in good agreement with data for intrinsic hydrogen diffusivity in the fibres Migration through pores along fibres with low activation energy may be considered as mechanism of deuterium penetration into the bulk of the CFC materials
Channels of D transport in CFC VAlimov et al
11
Fine grain graphite (as well as CFC) ndashtransparent for gases in principle
Penetrating gas flow via gas pressure for MPG-8 graphite (thickness 126 mm diameter 305 mm)
room temperature
Measured gas flux density j ~ σ P σ Ad
P ndashpressure A ndasharea d- thickness σ ndash specific gas permeability
σ = 5middot1015 mols for MPG-8
Flu
x m
ols
Pressure Pa
Graphite sheet behaves as capillary A=1m2 d =1cm P =1Pa 35middot1017 D2s
12
Influence of tokamak T-10 exposure on MPG-8 graphite permeability
MPG-8 membrane 18 mm thick cut off T-10 limiter demonstrated hydrogen permeability ~9middot1015 molmiddotc-1m-1Pa-1 - 2 times more than for ldquovirginrdquo graphite
Possible reason ndash graphite porosity increase after long term expose in tokamak
All attempts to increase MPG-8 permeability in lab plasma experiments failed
4 mm
Place of limiter tile used for the membrane
14
Comparison of lab experiments and tokamak exposed tile retention in CFC
TDS investigation of the samples CFC N11 implanted by deuterium ions in the laboratory setups (MEPhI) and high field side tile of Tore Supra
[1] Begrambekov L Brosset C Bucalossi J Delchambre E Gunn JP Grisolia C Lipa M Loarer T Mitteau R PMoner-Garbet P Pascal J-Y PShigin P Titov N Tsitrone E Vergazov S Zakharov A ldquoSurface modification and hydrogen isotope retention in CFC during plasma irradiation in the Tore Supra tokamakrdquo17th Internal Conference on Plasma Surface Interactions in Controlled Fusion Devices (PSI17) Hefei China May 22 ndash 26 2006
LABORATORY SAMPLE
TORE SUPRA TILE [1]
Particles deuterons deuterons
Ion energy 50 100 200
500 eV
10-100 eV (as well as low energy atoms molecules and charge exchange neutrals )
Ion flux density 1times1020 atm2s (1-2)times1019 atm2s
Fluence 5times1023 atm2 5times1023 atm2 (estimated)
Surface temperature 450-470 K up to 500-600 K
Retention ~07times1021 atm2 ~2times1022 atm2 (30 times higher)
15
Hydrogen retention via fluence in lab exp
1021 1022 1023 1024 10251020
1021
1022
Hyd
roge
n re
tent
ion
at
m2
Fluence atm2
B4C 100 eVH MPG-8 100 eVH MPG-8 1 keVH HPG99 1 keVH [1] HOPG 100 eVH HOPG 1 keVH
Ion flux density = 35x1020 at(secm2)
[2] L Begrambekov O Buzhinsky A Gordeev E Miljaeva P Leikin P Shigin TDS investigation of hydrogen retention in graphites and carbon based materials Physica scripta N108 (2004) p72-75
Possible underestimation of tokamak tile irradiation fluence hardly could seriously influence the presented data -hydrogen retention will not increase 30 times even for ~100 times higher fluence
16
Possible mechanisms of enhanced D
trapping under tokamak plasma irradiation
1 Presence of hydrogen in the Tore Supra tiles
TDS spectra of H2 and D2 for the as prepared CFC N11 samples irradiated in deuterium plasma
Ei = 100 eVat
Ji = 121020 atm2s
Ф = 451023 atm2
Presence of hydrogen in the CFC twice increases deuterium trapping at the expense of filling the hydrogen traps by deuterium due to isotope
exchange mechanism
Lab experiment
17
2 Trapping of deuterium activated by electron irradiation
[ Collaboration DRFC CEA-Cadarache ndash MEPhI ROSATOM 2007]
Thermal desorption of deuterium as D2
and as CD4 from CFC graphite under
ion and electron irradiationEi=100 eVat Ji=121020 atm2s
Ф=451023 atm2
Increase of deuterium retention along with irradiation time as well as deuterium retention under electron irradiation support an assumption about participation of D2
molecules from surrounding atmosphere in deuterium trapping into graphites Ion and electron irradiation act as a driving forces of the process
Plasma electron irradiation of CFC increased deuterium trapping 12 ndash 3 times depending on energy distribution of impinging deuterium particles
0 200 400 600 800 100000
05
10
15
Ret
entio
n x
1017
at
cm2
Energy eVat
CFC D2 (1020)
D2 electron irr
CFC D2 (2x1019)
electronirradiation
18
3 Transportation of deuterium into the material and trapping in the bulk of the tile
TDS analysis of the samples cut from different depth of the tile shows that more 10 of cumulative trapping collected in the bulk of tile
The samples of 1 ndash 2 mm thickness are usually used in the laboratory experiments The laboratory results could be compared
only to trapping in surface region of tokamak tile
4 Deuterium trapping in graphites irradiated by ion flux with wide energy distribution
Peculiarities of deuterium trapping in graphites exposed to plasma allows to expect an enhancement of retention in graphites irradiated by ion flux with wide energy distribution in tokamaks in comparison with graphites subjected to mono energy ion irradiation in laboratory
setups
19
5 Graphite surface irradiation during Helium Glow Discharge Conditioning
Helium ion bombardment leads to development of the surface relief and destruction of near surface layer As result trapping of deuterium during tokamak discharges should be enhanced
6 Graphite surface irradiation by oxygen impurities
Graphite irradiation by ions and atoms of oxygen impurities leads to accelerated surface destruction and develop the surface As a result trapping of deuterium ions and neutrals by graphite surface is probably more enhanced
20
Conclusion
bull The long range D retention in general is the very complicated physical (amp chemical) problem Many observed features of this phenomenon is not clear now
bull Complex and multiple-factor impact of PFM in tokamaks makes difficult distinguishing its influence on the LR hydrogen isotopes retention
bull Laboratory experiments with well defined impact parameters are crucially necessary
bull During last two years we mounted and calibrated a series of high vacuum installations with well controlled parameters for measurement of D retention in plasma exposed (as well in situ in simulators) samples and started comparative studies of samples radiated at different tokamaks and laboratory installations
21
Plansbull Investigations of samples irradiated in LENTA PR-2
PIN laboratory plasma facilities as well as in T-10 TEXTOR and Tore Supra tokamaks are now in progress
bull As there is very large scattering of the experimental data
on D retention careful measurements at D retention via fluxes (at high fluxes) and temperature in different irradiation facilities are under way
bull To pick up contribution of different factors on D retention step by step experimental investigations at varying definite factors (im flux density consequent and simultaneous irradiation with deuterium and helium broad energy spectra influence etc) are planned
bull Experimental measurements of neutron irradiation influence on hydrogen isotopes retention in PFM is now discussed
- Slide 1
- Slide 2
- Slide 3
- Slide 4
- Slide 5
- Slide 6
- Slide 7
- Slide 8
- Slide 9
- Slide 10
- Slide 11
- Slide 12
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- Slide 21
-
5
0 50 100 1500
1
2
3
2
1
Depth nm
Con
cent
rati
on a
t
Deuterium concentration profiles in V-349Ga alloy after irradiation with pulsed deuterium plasma (15 pulses 028 MJm2) 1 ndash backside 2 ndash irradiated side 3- non irradiated(ERDA 2-MeV He+)
0 50 100 1500
5
10
15
3
2
1
Con
cent
rati
on a
t
Depth nm
Hydrogen concentration profiles in V-349Ga alloy after irradiation with 6-keV H+ ions in ion accelerator ILU at dose 10 1023 м-2 and target temperature Т = 4500С 1 ndash irradiated side 2 - backside 3 ndash non irradiates sample(ERDA 2-MeV He+)
Surer deep hydrogen penetration in vanadium alloy (2)
6
0
200
400c
0
200
400b
Depth m
0
200
400а
Mic
roh
ard
nes
s k
gm
m2
0 100 200 300 400 100 0
Microhardness as a function of depth measured on samples cross section after stationary plasma irradiation ( ndash irradiated side - back side - before irradiation) а) V-10Ti-6Cr-005Zr ndash irradiation time 20 min (D= 22 1024 m-2)b) V-10Ti-6Cr-005Zr ndash irradiation time 1 hour (D= 64 1024 m-2) c) V-15Ti-10Cr-005Y - irradiation time 1 hour (D= 64 1024 m-2)
Hydrogen irradiation induceddeep strengthening
Stationary pulsed power hydrogen plasma and 6-keV H+ ions irradiation results in deep strengthening ndash a reason is hydrates formation which create compressive stress in material
Preprint 64527 Kurchatov Institute
Before irradiation
backside
7
0 1 2 3 4 510-2
10-1
100
101
0 1 2 3 4 510-2
10-1
100
101
a)
W2C + 10 at C
200 eV D plasma CVD coatings 2x1024 Dm2
D c
on
ce
ntr
atio
n [a
t
]
Texp
= 373 K T
exp = 433 K
Texp
= 503 K
b)
WC + 10 at C
Texp
= 413 K T
exp = 543 K
Texp
= 653 K T
exp = 813 K
D c
on
ce
ntr
atio
n [a
t
]
Depth [m]
NRA analysis of CVD W2C amp WC coatings (VAlimov et al)
At temperatures above 550 K D concentration in the bulk starts to decrease
Presumably deuterium is retained in carbon precipitates
8
Mechanisms of long range D transportYuMartynenko et al
Shock wave initiation
ion
Cascade of displacements
defects
Physical interpretation connected with generation and transport of dislocation loops under influence of surface layer tension generation of thermoelastic tension and shock waves that force diffusion of admixtures along interstitials and grain borders
9
But physical mechanisms are far from full understanding
For adequate explanation versatile investigations using novel experimental methods as well as intimate theoretical analysis are necessary
For chemical active C based materials with compound structure (CFC) the task is much more complicated and need very careful investigations
10
0 2 4 6 8 1010-3
10-2
10-1
100
101 200 eV D plasma CFC NB31 2x1024 Dm2
Texp
= 463 K T
exp = 673 K
Texp
= 773 K T
exp = 948 K
D c
once
ntra
tion
[at
]
Depth [m]
0( ) [1 erf( )]2
xC x C
Dt
Migration in the bulk obeys diffusion equation with D=D(Fluence Temp)
10 15 20 25 3010-17
10-15
10-13
10-11
10-9
10-7
NB31 200 eV D plasma (Magnetron)
Coe
ffici
ent o
f D m
igra
tion
[m2 s
]
1000Temperature [K-1]
LA Sedano et al (1998) NB11 Matrix N11 Matrix NB11 Fibres N11 Fibres
Values for the deuterium migration derived from the D depth profiles are in good agreement with data for intrinsic hydrogen diffusivity in the fibres Migration through pores along fibres with low activation energy may be considered as mechanism of deuterium penetration into the bulk of the CFC materials
Channels of D transport in CFC VAlimov et al
11
Fine grain graphite (as well as CFC) ndashtransparent for gases in principle
Penetrating gas flow via gas pressure for MPG-8 graphite (thickness 126 mm diameter 305 mm)
room temperature
Measured gas flux density j ~ σ P σ Ad
P ndashpressure A ndasharea d- thickness σ ndash specific gas permeability
σ = 5middot1015 mols for MPG-8
Flu
x m
ols
Pressure Pa
Graphite sheet behaves as capillary A=1m2 d =1cm P =1Pa 35middot1017 D2s
12
Influence of tokamak T-10 exposure on MPG-8 graphite permeability
MPG-8 membrane 18 mm thick cut off T-10 limiter demonstrated hydrogen permeability ~9middot1015 molmiddotc-1m-1Pa-1 - 2 times more than for ldquovirginrdquo graphite
Possible reason ndash graphite porosity increase after long term expose in tokamak
All attempts to increase MPG-8 permeability in lab plasma experiments failed
4 mm
Place of limiter tile used for the membrane
14
Comparison of lab experiments and tokamak exposed tile retention in CFC
TDS investigation of the samples CFC N11 implanted by deuterium ions in the laboratory setups (MEPhI) and high field side tile of Tore Supra
[1] Begrambekov L Brosset C Bucalossi J Delchambre E Gunn JP Grisolia C Lipa M Loarer T Mitteau R PMoner-Garbet P Pascal J-Y PShigin P Titov N Tsitrone E Vergazov S Zakharov A ldquoSurface modification and hydrogen isotope retention in CFC during plasma irradiation in the Tore Supra tokamakrdquo17th Internal Conference on Plasma Surface Interactions in Controlled Fusion Devices (PSI17) Hefei China May 22 ndash 26 2006
LABORATORY SAMPLE
TORE SUPRA TILE [1]
Particles deuterons deuterons
Ion energy 50 100 200
500 eV
10-100 eV (as well as low energy atoms molecules and charge exchange neutrals )
Ion flux density 1times1020 atm2s (1-2)times1019 atm2s
Fluence 5times1023 atm2 5times1023 atm2 (estimated)
Surface temperature 450-470 K up to 500-600 K
Retention ~07times1021 atm2 ~2times1022 atm2 (30 times higher)
15
Hydrogen retention via fluence in lab exp
1021 1022 1023 1024 10251020
1021
1022
Hyd
roge
n re
tent
ion
at
m2
Fluence atm2
B4C 100 eVH MPG-8 100 eVH MPG-8 1 keVH HPG99 1 keVH [1] HOPG 100 eVH HOPG 1 keVH
Ion flux density = 35x1020 at(secm2)
[2] L Begrambekov O Buzhinsky A Gordeev E Miljaeva P Leikin P Shigin TDS investigation of hydrogen retention in graphites and carbon based materials Physica scripta N108 (2004) p72-75
Possible underestimation of tokamak tile irradiation fluence hardly could seriously influence the presented data -hydrogen retention will not increase 30 times even for ~100 times higher fluence
16
Possible mechanisms of enhanced D
trapping under tokamak plasma irradiation
1 Presence of hydrogen in the Tore Supra tiles
TDS spectra of H2 and D2 for the as prepared CFC N11 samples irradiated in deuterium plasma
Ei = 100 eVat
Ji = 121020 atm2s
Ф = 451023 atm2
Presence of hydrogen in the CFC twice increases deuterium trapping at the expense of filling the hydrogen traps by deuterium due to isotope
exchange mechanism
Lab experiment
17
2 Trapping of deuterium activated by electron irradiation
[ Collaboration DRFC CEA-Cadarache ndash MEPhI ROSATOM 2007]
Thermal desorption of deuterium as D2
and as CD4 from CFC graphite under
ion and electron irradiationEi=100 eVat Ji=121020 atm2s
Ф=451023 atm2
Increase of deuterium retention along with irradiation time as well as deuterium retention under electron irradiation support an assumption about participation of D2
molecules from surrounding atmosphere in deuterium trapping into graphites Ion and electron irradiation act as a driving forces of the process
Plasma electron irradiation of CFC increased deuterium trapping 12 ndash 3 times depending on energy distribution of impinging deuterium particles
0 200 400 600 800 100000
05
10
15
Ret
entio
n x
1017
at
cm2
Energy eVat
CFC D2 (1020)
D2 electron irr
CFC D2 (2x1019)
electronirradiation
18
3 Transportation of deuterium into the material and trapping in the bulk of the tile
TDS analysis of the samples cut from different depth of the tile shows that more 10 of cumulative trapping collected in the bulk of tile
The samples of 1 ndash 2 mm thickness are usually used in the laboratory experiments The laboratory results could be compared
only to trapping in surface region of tokamak tile
4 Deuterium trapping in graphites irradiated by ion flux with wide energy distribution
Peculiarities of deuterium trapping in graphites exposed to plasma allows to expect an enhancement of retention in graphites irradiated by ion flux with wide energy distribution in tokamaks in comparison with graphites subjected to mono energy ion irradiation in laboratory
setups
19
5 Graphite surface irradiation during Helium Glow Discharge Conditioning
Helium ion bombardment leads to development of the surface relief and destruction of near surface layer As result trapping of deuterium during tokamak discharges should be enhanced
6 Graphite surface irradiation by oxygen impurities
Graphite irradiation by ions and atoms of oxygen impurities leads to accelerated surface destruction and develop the surface As a result trapping of deuterium ions and neutrals by graphite surface is probably more enhanced
20
Conclusion
bull The long range D retention in general is the very complicated physical (amp chemical) problem Many observed features of this phenomenon is not clear now
bull Complex and multiple-factor impact of PFM in tokamaks makes difficult distinguishing its influence on the LR hydrogen isotopes retention
bull Laboratory experiments with well defined impact parameters are crucially necessary
bull During last two years we mounted and calibrated a series of high vacuum installations with well controlled parameters for measurement of D retention in plasma exposed (as well in situ in simulators) samples and started comparative studies of samples radiated at different tokamaks and laboratory installations
21
Plansbull Investigations of samples irradiated in LENTA PR-2
PIN laboratory plasma facilities as well as in T-10 TEXTOR and Tore Supra tokamaks are now in progress
bull As there is very large scattering of the experimental data
on D retention careful measurements at D retention via fluxes (at high fluxes) and temperature in different irradiation facilities are under way
bull To pick up contribution of different factors on D retention step by step experimental investigations at varying definite factors (im flux density consequent and simultaneous irradiation with deuterium and helium broad energy spectra influence etc) are planned
bull Experimental measurements of neutron irradiation influence on hydrogen isotopes retention in PFM is now discussed
- Slide 1
- Slide 2
- Slide 3
- Slide 4
- Slide 5
- Slide 6
- Slide 7
- Slide 8
- Slide 9
- Slide 10
- Slide 11
- Slide 12
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- Slide 21
-
6
0
200
400c
0
200
400b
Depth m
0
200
400а
Mic
roh
ard
nes
s k
gm
m2
0 100 200 300 400 100 0
Microhardness as a function of depth measured on samples cross section after stationary plasma irradiation ( ndash irradiated side - back side - before irradiation) а) V-10Ti-6Cr-005Zr ndash irradiation time 20 min (D= 22 1024 m-2)b) V-10Ti-6Cr-005Zr ndash irradiation time 1 hour (D= 64 1024 m-2) c) V-15Ti-10Cr-005Y - irradiation time 1 hour (D= 64 1024 m-2)
Hydrogen irradiation induceddeep strengthening
Stationary pulsed power hydrogen plasma and 6-keV H+ ions irradiation results in deep strengthening ndash a reason is hydrates formation which create compressive stress in material
Preprint 64527 Kurchatov Institute
Before irradiation
backside
7
0 1 2 3 4 510-2
10-1
100
101
0 1 2 3 4 510-2
10-1
100
101
a)
W2C + 10 at C
200 eV D plasma CVD coatings 2x1024 Dm2
D c
on
ce
ntr
atio
n [a
t
]
Texp
= 373 K T
exp = 433 K
Texp
= 503 K
b)
WC + 10 at C
Texp
= 413 K T
exp = 543 K
Texp
= 653 K T
exp = 813 K
D c
on
ce
ntr
atio
n [a
t
]
Depth [m]
NRA analysis of CVD W2C amp WC coatings (VAlimov et al)
At temperatures above 550 K D concentration in the bulk starts to decrease
Presumably deuterium is retained in carbon precipitates
8
Mechanisms of long range D transportYuMartynenko et al
Shock wave initiation
ion
Cascade of displacements
defects
Physical interpretation connected with generation and transport of dislocation loops under influence of surface layer tension generation of thermoelastic tension and shock waves that force diffusion of admixtures along interstitials and grain borders
9
But physical mechanisms are far from full understanding
For adequate explanation versatile investigations using novel experimental methods as well as intimate theoretical analysis are necessary
For chemical active C based materials with compound structure (CFC) the task is much more complicated and need very careful investigations
10
0 2 4 6 8 1010-3
10-2
10-1
100
101 200 eV D plasma CFC NB31 2x1024 Dm2
Texp
= 463 K T
exp = 673 K
Texp
= 773 K T
exp = 948 K
D c
once
ntra
tion
[at
]
Depth [m]
0( ) [1 erf( )]2
xC x C
Dt
Migration in the bulk obeys diffusion equation with D=D(Fluence Temp)
10 15 20 25 3010-17
10-15
10-13
10-11
10-9
10-7
NB31 200 eV D plasma (Magnetron)
Coe
ffici
ent o
f D m
igra
tion
[m2 s
]
1000Temperature [K-1]
LA Sedano et al (1998) NB11 Matrix N11 Matrix NB11 Fibres N11 Fibres
Values for the deuterium migration derived from the D depth profiles are in good agreement with data for intrinsic hydrogen diffusivity in the fibres Migration through pores along fibres with low activation energy may be considered as mechanism of deuterium penetration into the bulk of the CFC materials
Channels of D transport in CFC VAlimov et al
11
Fine grain graphite (as well as CFC) ndashtransparent for gases in principle
Penetrating gas flow via gas pressure for MPG-8 graphite (thickness 126 mm diameter 305 mm)
room temperature
Measured gas flux density j ~ σ P σ Ad
P ndashpressure A ndasharea d- thickness σ ndash specific gas permeability
σ = 5middot1015 mols for MPG-8
Flu
x m
ols
Pressure Pa
Graphite sheet behaves as capillary A=1m2 d =1cm P =1Pa 35middot1017 D2s
12
Influence of tokamak T-10 exposure on MPG-8 graphite permeability
MPG-8 membrane 18 mm thick cut off T-10 limiter demonstrated hydrogen permeability ~9middot1015 molmiddotc-1m-1Pa-1 - 2 times more than for ldquovirginrdquo graphite
Possible reason ndash graphite porosity increase after long term expose in tokamak
All attempts to increase MPG-8 permeability in lab plasma experiments failed
4 mm
Place of limiter tile used for the membrane
14
Comparison of lab experiments and tokamak exposed tile retention in CFC
TDS investigation of the samples CFC N11 implanted by deuterium ions in the laboratory setups (MEPhI) and high field side tile of Tore Supra
[1] Begrambekov L Brosset C Bucalossi J Delchambre E Gunn JP Grisolia C Lipa M Loarer T Mitteau R PMoner-Garbet P Pascal J-Y PShigin P Titov N Tsitrone E Vergazov S Zakharov A ldquoSurface modification and hydrogen isotope retention in CFC during plasma irradiation in the Tore Supra tokamakrdquo17th Internal Conference on Plasma Surface Interactions in Controlled Fusion Devices (PSI17) Hefei China May 22 ndash 26 2006
LABORATORY SAMPLE
TORE SUPRA TILE [1]
Particles deuterons deuterons
Ion energy 50 100 200
500 eV
10-100 eV (as well as low energy atoms molecules and charge exchange neutrals )
Ion flux density 1times1020 atm2s (1-2)times1019 atm2s
Fluence 5times1023 atm2 5times1023 atm2 (estimated)
Surface temperature 450-470 K up to 500-600 K
Retention ~07times1021 atm2 ~2times1022 atm2 (30 times higher)
15
Hydrogen retention via fluence in lab exp
1021 1022 1023 1024 10251020
1021
1022
Hyd
roge
n re
tent
ion
at
m2
Fluence atm2
B4C 100 eVH MPG-8 100 eVH MPG-8 1 keVH HPG99 1 keVH [1] HOPG 100 eVH HOPG 1 keVH
Ion flux density = 35x1020 at(secm2)
[2] L Begrambekov O Buzhinsky A Gordeev E Miljaeva P Leikin P Shigin TDS investigation of hydrogen retention in graphites and carbon based materials Physica scripta N108 (2004) p72-75
Possible underestimation of tokamak tile irradiation fluence hardly could seriously influence the presented data -hydrogen retention will not increase 30 times even for ~100 times higher fluence
16
Possible mechanisms of enhanced D
trapping under tokamak plasma irradiation
1 Presence of hydrogen in the Tore Supra tiles
TDS spectra of H2 and D2 for the as prepared CFC N11 samples irradiated in deuterium plasma
Ei = 100 eVat
Ji = 121020 atm2s
Ф = 451023 atm2
Presence of hydrogen in the CFC twice increases deuterium trapping at the expense of filling the hydrogen traps by deuterium due to isotope
exchange mechanism
Lab experiment
17
2 Trapping of deuterium activated by electron irradiation
[ Collaboration DRFC CEA-Cadarache ndash MEPhI ROSATOM 2007]
Thermal desorption of deuterium as D2
and as CD4 from CFC graphite under
ion and electron irradiationEi=100 eVat Ji=121020 atm2s
Ф=451023 atm2
Increase of deuterium retention along with irradiation time as well as deuterium retention under electron irradiation support an assumption about participation of D2
molecules from surrounding atmosphere in deuterium trapping into graphites Ion and electron irradiation act as a driving forces of the process
Plasma electron irradiation of CFC increased deuterium trapping 12 ndash 3 times depending on energy distribution of impinging deuterium particles
0 200 400 600 800 100000
05
10
15
Ret
entio
n x
1017
at
cm2
Energy eVat
CFC D2 (1020)
D2 electron irr
CFC D2 (2x1019)
electronirradiation
18
3 Transportation of deuterium into the material and trapping in the bulk of the tile
TDS analysis of the samples cut from different depth of the tile shows that more 10 of cumulative trapping collected in the bulk of tile
The samples of 1 ndash 2 mm thickness are usually used in the laboratory experiments The laboratory results could be compared
only to trapping in surface region of tokamak tile
4 Deuterium trapping in graphites irradiated by ion flux with wide energy distribution
Peculiarities of deuterium trapping in graphites exposed to plasma allows to expect an enhancement of retention in graphites irradiated by ion flux with wide energy distribution in tokamaks in comparison with graphites subjected to mono energy ion irradiation in laboratory
setups
19
5 Graphite surface irradiation during Helium Glow Discharge Conditioning
Helium ion bombardment leads to development of the surface relief and destruction of near surface layer As result trapping of deuterium during tokamak discharges should be enhanced
6 Graphite surface irradiation by oxygen impurities
Graphite irradiation by ions and atoms of oxygen impurities leads to accelerated surface destruction and develop the surface As a result trapping of deuterium ions and neutrals by graphite surface is probably more enhanced
20
Conclusion
bull The long range D retention in general is the very complicated physical (amp chemical) problem Many observed features of this phenomenon is not clear now
bull Complex and multiple-factor impact of PFM in tokamaks makes difficult distinguishing its influence on the LR hydrogen isotopes retention
bull Laboratory experiments with well defined impact parameters are crucially necessary
bull During last two years we mounted and calibrated a series of high vacuum installations with well controlled parameters for measurement of D retention in plasma exposed (as well in situ in simulators) samples and started comparative studies of samples radiated at different tokamaks and laboratory installations
21
Plansbull Investigations of samples irradiated in LENTA PR-2
PIN laboratory plasma facilities as well as in T-10 TEXTOR and Tore Supra tokamaks are now in progress
bull As there is very large scattering of the experimental data
on D retention careful measurements at D retention via fluxes (at high fluxes) and temperature in different irradiation facilities are under way
bull To pick up contribution of different factors on D retention step by step experimental investigations at varying definite factors (im flux density consequent and simultaneous irradiation with deuterium and helium broad energy spectra influence etc) are planned
bull Experimental measurements of neutron irradiation influence on hydrogen isotopes retention in PFM is now discussed
- Slide 1
- Slide 2
- Slide 3
- Slide 4
- Slide 5
- Slide 6
- Slide 7
- Slide 8
- Slide 9
- Slide 10
- Slide 11
- Slide 12
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- Slide 21
-
7
0 1 2 3 4 510-2
10-1
100
101
0 1 2 3 4 510-2
10-1
100
101
a)
W2C + 10 at C
200 eV D plasma CVD coatings 2x1024 Dm2
D c
on
ce
ntr
atio
n [a
t
]
Texp
= 373 K T
exp = 433 K
Texp
= 503 K
b)
WC + 10 at C
Texp
= 413 K T
exp = 543 K
Texp
= 653 K T
exp = 813 K
D c
on
ce
ntr
atio
n [a
t
]
Depth [m]
NRA analysis of CVD W2C amp WC coatings (VAlimov et al)
At temperatures above 550 K D concentration in the bulk starts to decrease
Presumably deuterium is retained in carbon precipitates
8
Mechanisms of long range D transportYuMartynenko et al
Shock wave initiation
ion
Cascade of displacements
defects
Physical interpretation connected with generation and transport of dislocation loops under influence of surface layer tension generation of thermoelastic tension and shock waves that force diffusion of admixtures along interstitials and grain borders
9
But physical mechanisms are far from full understanding
For adequate explanation versatile investigations using novel experimental methods as well as intimate theoretical analysis are necessary
For chemical active C based materials with compound structure (CFC) the task is much more complicated and need very careful investigations
10
0 2 4 6 8 1010-3
10-2
10-1
100
101 200 eV D plasma CFC NB31 2x1024 Dm2
Texp
= 463 K T
exp = 673 K
Texp
= 773 K T
exp = 948 K
D c
once
ntra
tion
[at
]
Depth [m]
0( ) [1 erf( )]2
xC x C
Dt
Migration in the bulk obeys diffusion equation with D=D(Fluence Temp)
10 15 20 25 3010-17
10-15
10-13
10-11
10-9
10-7
NB31 200 eV D plasma (Magnetron)
Coe
ffici
ent o
f D m
igra
tion
[m2 s
]
1000Temperature [K-1]
LA Sedano et al (1998) NB11 Matrix N11 Matrix NB11 Fibres N11 Fibres
Values for the deuterium migration derived from the D depth profiles are in good agreement with data for intrinsic hydrogen diffusivity in the fibres Migration through pores along fibres with low activation energy may be considered as mechanism of deuterium penetration into the bulk of the CFC materials
Channels of D transport in CFC VAlimov et al
11
Fine grain graphite (as well as CFC) ndashtransparent for gases in principle
Penetrating gas flow via gas pressure for MPG-8 graphite (thickness 126 mm diameter 305 mm)
room temperature
Measured gas flux density j ~ σ P σ Ad
P ndashpressure A ndasharea d- thickness σ ndash specific gas permeability
σ = 5middot1015 mols for MPG-8
Flu
x m
ols
Pressure Pa
Graphite sheet behaves as capillary A=1m2 d =1cm P =1Pa 35middot1017 D2s
12
Influence of tokamak T-10 exposure on MPG-8 graphite permeability
MPG-8 membrane 18 mm thick cut off T-10 limiter demonstrated hydrogen permeability ~9middot1015 molmiddotc-1m-1Pa-1 - 2 times more than for ldquovirginrdquo graphite
Possible reason ndash graphite porosity increase after long term expose in tokamak
All attempts to increase MPG-8 permeability in lab plasma experiments failed
4 mm
Place of limiter tile used for the membrane
14
Comparison of lab experiments and tokamak exposed tile retention in CFC
TDS investigation of the samples CFC N11 implanted by deuterium ions in the laboratory setups (MEPhI) and high field side tile of Tore Supra
[1] Begrambekov L Brosset C Bucalossi J Delchambre E Gunn JP Grisolia C Lipa M Loarer T Mitteau R PMoner-Garbet P Pascal J-Y PShigin P Titov N Tsitrone E Vergazov S Zakharov A ldquoSurface modification and hydrogen isotope retention in CFC during plasma irradiation in the Tore Supra tokamakrdquo17th Internal Conference on Plasma Surface Interactions in Controlled Fusion Devices (PSI17) Hefei China May 22 ndash 26 2006
LABORATORY SAMPLE
TORE SUPRA TILE [1]
Particles deuterons deuterons
Ion energy 50 100 200
500 eV
10-100 eV (as well as low energy atoms molecules and charge exchange neutrals )
Ion flux density 1times1020 atm2s (1-2)times1019 atm2s
Fluence 5times1023 atm2 5times1023 atm2 (estimated)
Surface temperature 450-470 K up to 500-600 K
Retention ~07times1021 atm2 ~2times1022 atm2 (30 times higher)
15
Hydrogen retention via fluence in lab exp
1021 1022 1023 1024 10251020
1021
1022
Hyd
roge
n re
tent
ion
at
m2
Fluence atm2
B4C 100 eVH MPG-8 100 eVH MPG-8 1 keVH HPG99 1 keVH [1] HOPG 100 eVH HOPG 1 keVH
Ion flux density = 35x1020 at(secm2)
[2] L Begrambekov O Buzhinsky A Gordeev E Miljaeva P Leikin P Shigin TDS investigation of hydrogen retention in graphites and carbon based materials Physica scripta N108 (2004) p72-75
Possible underestimation of tokamak tile irradiation fluence hardly could seriously influence the presented data -hydrogen retention will not increase 30 times even for ~100 times higher fluence
16
Possible mechanisms of enhanced D
trapping under tokamak plasma irradiation
1 Presence of hydrogen in the Tore Supra tiles
TDS spectra of H2 and D2 for the as prepared CFC N11 samples irradiated in deuterium plasma
Ei = 100 eVat
Ji = 121020 atm2s
Ф = 451023 atm2
Presence of hydrogen in the CFC twice increases deuterium trapping at the expense of filling the hydrogen traps by deuterium due to isotope
exchange mechanism
Lab experiment
17
2 Trapping of deuterium activated by electron irradiation
[ Collaboration DRFC CEA-Cadarache ndash MEPhI ROSATOM 2007]
Thermal desorption of deuterium as D2
and as CD4 from CFC graphite under
ion and electron irradiationEi=100 eVat Ji=121020 atm2s
Ф=451023 atm2
Increase of deuterium retention along with irradiation time as well as deuterium retention under electron irradiation support an assumption about participation of D2
molecules from surrounding atmosphere in deuterium trapping into graphites Ion and electron irradiation act as a driving forces of the process
Plasma electron irradiation of CFC increased deuterium trapping 12 ndash 3 times depending on energy distribution of impinging deuterium particles
0 200 400 600 800 100000
05
10
15
Ret
entio
n x
1017
at
cm2
Energy eVat
CFC D2 (1020)
D2 electron irr
CFC D2 (2x1019)
electronirradiation
18
3 Transportation of deuterium into the material and trapping in the bulk of the tile
TDS analysis of the samples cut from different depth of the tile shows that more 10 of cumulative trapping collected in the bulk of tile
The samples of 1 ndash 2 mm thickness are usually used in the laboratory experiments The laboratory results could be compared
only to trapping in surface region of tokamak tile
4 Deuterium trapping in graphites irradiated by ion flux with wide energy distribution
Peculiarities of deuterium trapping in graphites exposed to plasma allows to expect an enhancement of retention in graphites irradiated by ion flux with wide energy distribution in tokamaks in comparison with graphites subjected to mono energy ion irradiation in laboratory
setups
19
5 Graphite surface irradiation during Helium Glow Discharge Conditioning
Helium ion bombardment leads to development of the surface relief and destruction of near surface layer As result trapping of deuterium during tokamak discharges should be enhanced
6 Graphite surface irradiation by oxygen impurities
Graphite irradiation by ions and atoms of oxygen impurities leads to accelerated surface destruction and develop the surface As a result trapping of deuterium ions and neutrals by graphite surface is probably more enhanced
20
Conclusion
bull The long range D retention in general is the very complicated physical (amp chemical) problem Many observed features of this phenomenon is not clear now
bull Complex and multiple-factor impact of PFM in tokamaks makes difficult distinguishing its influence on the LR hydrogen isotopes retention
bull Laboratory experiments with well defined impact parameters are crucially necessary
bull During last two years we mounted and calibrated a series of high vacuum installations with well controlled parameters for measurement of D retention in plasma exposed (as well in situ in simulators) samples and started comparative studies of samples radiated at different tokamaks and laboratory installations
21
Plansbull Investigations of samples irradiated in LENTA PR-2
PIN laboratory plasma facilities as well as in T-10 TEXTOR and Tore Supra tokamaks are now in progress
bull As there is very large scattering of the experimental data
on D retention careful measurements at D retention via fluxes (at high fluxes) and temperature in different irradiation facilities are under way
bull To pick up contribution of different factors on D retention step by step experimental investigations at varying definite factors (im flux density consequent and simultaneous irradiation with deuterium and helium broad energy spectra influence etc) are planned
bull Experimental measurements of neutron irradiation influence on hydrogen isotopes retention in PFM is now discussed
- Slide 1
- Slide 2
- Slide 3
- Slide 4
- Slide 5
- Slide 6
- Slide 7
- Slide 8
- Slide 9
- Slide 10
- Slide 11
- Slide 12
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- Slide 21
-
8
Mechanisms of long range D transportYuMartynenko et al
Shock wave initiation
ion
Cascade of displacements
defects
Physical interpretation connected with generation and transport of dislocation loops under influence of surface layer tension generation of thermoelastic tension and shock waves that force diffusion of admixtures along interstitials and grain borders
9
But physical mechanisms are far from full understanding
For adequate explanation versatile investigations using novel experimental methods as well as intimate theoretical analysis are necessary
For chemical active C based materials with compound structure (CFC) the task is much more complicated and need very careful investigations
10
0 2 4 6 8 1010-3
10-2
10-1
100
101 200 eV D plasma CFC NB31 2x1024 Dm2
Texp
= 463 K T
exp = 673 K
Texp
= 773 K T
exp = 948 K
D c
once
ntra
tion
[at
]
Depth [m]
0( ) [1 erf( )]2
xC x C
Dt
Migration in the bulk obeys diffusion equation with D=D(Fluence Temp)
10 15 20 25 3010-17
10-15
10-13
10-11
10-9
10-7
NB31 200 eV D plasma (Magnetron)
Coe
ffici
ent o
f D m
igra
tion
[m2 s
]
1000Temperature [K-1]
LA Sedano et al (1998) NB11 Matrix N11 Matrix NB11 Fibres N11 Fibres
Values for the deuterium migration derived from the D depth profiles are in good agreement with data for intrinsic hydrogen diffusivity in the fibres Migration through pores along fibres with low activation energy may be considered as mechanism of deuterium penetration into the bulk of the CFC materials
Channels of D transport in CFC VAlimov et al
11
Fine grain graphite (as well as CFC) ndashtransparent for gases in principle
Penetrating gas flow via gas pressure for MPG-8 graphite (thickness 126 mm diameter 305 mm)
room temperature
Measured gas flux density j ~ σ P σ Ad
P ndashpressure A ndasharea d- thickness σ ndash specific gas permeability
σ = 5middot1015 mols for MPG-8
Flu
x m
ols
Pressure Pa
Graphite sheet behaves as capillary A=1m2 d =1cm P =1Pa 35middot1017 D2s
12
Influence of tokamak T-10 exposure on MPG-8 graphite permeability
MPG-8 membrane 18 mm thick cut off T-10 limiter demonstrated hydrogen permeability ~9middot1015 molmiddotc-1m-1Pa-1 - 2 times more than for ldquovirginrdquo graphite
Possible reason ndash graphite porosity increase after long term expose in tokamak
All attempts to increase MPG-8 permeability in lab plasma experiments failed
4 mm
Place of limiter tile used for the membrane
14
Comparison of lab experiments and tokamak exposed tile retention in CFC
TDS investigation of the samples CFC N11 implanted by deuterium ions in the laboratory setups (MEPhI) and high field side tile of Tore Supra
[1] Begrambekov L Brosset C Bucalossi J Delchambre E Gunn JP Grisolia C Lipa M Loarer T Mitteau R PMoner-Garbet P Pascal J-Y PShigin P Titov N Tsitrone E Vergazov S Zakharov A ldquoSurface modification and hydrogen isotope retention in CFC during plasma irradiation in the Tore Supra tokamakrdquo17th Internal Conference on Plasma Surface Interactions in Controlled Fusion Devices (PSI17) Hefei China May 22 ndash 26 2006
LABORATORY SAMPLE
TORE SUPRA TILE [1]
Particles deuterons deuterons
Ion energy 50 100 200
500 eV
10-100 eV (as well as low energy atoms molecules and charge exchange neutrals )
Ion flux density 1times1020 atm2s (1-2)times1019 atm2s
Fluence 5times1023 atm2 5times1023 atm2 (estimated)
Surface temperature 450-470 K up to 500-600 K
Retention ~07times1021 atm2 ~2times1022 atm2 (30 times higher)
15
Hydrogen retention via fluence in lab exp
1021 1022 1023 1024 10251020
1021
1022
Hyd
roge
n re
tent
ion
at
m2
Fluence atm2
B4C 100 eVH MPG-8 100 eVH MPG-8 1 keVH HPG99 1 keVH [1] HOPG 100 eVH HOPG 1 keVH
Ion flux density = 35x1020 at(secm2)
[2] L Begrambekov O Buzhinsky A Gordeev E Miljaeva P Leikin P Shigin TDS investigation of hydrogen retention in graphites and carbon based materials Physica scripta N108 (2004) p72-75
Possible underestimation of tokamak tile irradiation fluence hardly could seriously influence the presented data -hydrogen retention will not increase 30 times even for ~100 times higher fluence
16
Possible mechanisms of enhanced D
trapping under tokamak plasma irradiation
1 Presence of hydrogen in the Tore Supra tiles
TDS spectra of H2 and D2 for the as prepared CFC N11 samples irradiated in deuterium plasma
Ei = 100 eVat
Ji = 121020 atm2s
Ф = 451023 atm2
Presence of hydrogen in the CFC twice increases deuterium trapping at the expense of filling the hydrogen traps by deuterium due to isotope
exchange mechanism
Lab experiment
17
2 Trapping of deuterium activated by electron irradiation
[ Collaboration DRFC CEA-Cadarache ndash MEPhI ROSATOM 2007]
Thermal desorption of deuterium as D2
and as CD4 from CFC graphite under
ion and electron irradiationEi=100 eVat Ji=121020 atm2s
Ф=451023 atm2
Increase of deuterium retention along with irradiation time as well as deuterium retention under electron irradiation support an assumption about participation of D2
molecules from surrounding atmosphere in deuterium trapping into graphites Ion and electron irradiation act as a driving forces of the process
Plasma electron irradiation of CFC increased deuterium trapping 12 ndash 3 times depending on energy distribution of impinging deuterium particles
0 200 400 600 800 100000
05
10
15
Ret
entio
n x
1017
at
cm2
Energy eVat
CFC D2 (1020)
D2 electron irr
CFC D2 (2x1019)
electronirradiation
18
3 Transportation of deuterium into the material and trapping in the bulk of the tile
TDS analysis of the samples cut from different depth of the tile shows that more 10 of cumulative trapping collected in the bulk of tile
The samples of 1 ndash 2 mm thickness are usually used in the laboratory experiments The laboratory results could be compared
only to trapping in surface region of tokamak tile
4 Deuterium trapping in graphites irradiated by ion flux with wide energy distribution
Peculiarities of deuterium trapping in graphites exposed to plasma allows to expect an enhancement of retention in graphites irradiated by ion flux with wide energy distribution in tokamaks in comparison with graphites subjected to mono energy ion irradiation in laboratory
setups
19
5 Graphite surface irradiation during Helium Glow Discharge Conditioning
Helium ion bombardment leads to development of the surface relief and destruction of near surface layer As result trapping of deuterium during tokamak discharges should be enhanced
6 Graphite surface irradiation by oxygen impurities
Graphite irradiation by ions and atoms of oxygen impurities leads to accelerated surface destruction and develop the surface As a result trapping of deuterium ions and neutrals by graphite surface is probably more enhanced
20
Conclusion
bull The long range D retention in general is the very complicated physical (amp chemical) problem Many observed features of this phenomenon is not clear now
bull Complex and multiple-factor impact of PFM in tokamaks makes difficult distinguishing its influence on the LR hydrogen isotopes retention
bull Laboratory experiments with well defined impact parameters are crucially necessary
bull During last two years we mounted and calibrated a series of high vacuum installations with well controlled parameters for measurement of D retention in plasma exposed (as well in situ in simulators) samples and started comparative studies of samples radiated at different tokamaks and laboratory installations
21
Plansbull Investigations of samples irradiated in LENTA PR-2
PIN laboratory plasma facilities as well as in T-10 TEXTOR and Tore Supra tokamaks are now in progress
bull As there is very large scattering of the experimental data
on D retention careful measurements at D retention via fluxes (at high fluxes) and temperature in different irradiation facilities are under way
bull To pick up contribution of different factors on D retention step by step experimental investigations at varying definite factors (im flux density consequent and simultaneous irradiation with deuterium and helium broad energy spectra influence etc) are planned
bull Experimental measurements of neutron irradiation influence on hydrogen isotopes retention in PFM is now discussed
- Slide 1
- Slide 2
- Slide 3
- Slide 4
- Slide 5
- Slide 6
- Slide 7
- Slide 8
- Slide 9
- Slide 10
- Slide 11
- Slide 12
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- Slide 21
-
9
But physical mechanisms are far from full understanding
For adequate explanation versatile investigations using novel experimental methods as well as intimate theoretical analysis are necessary
For chemical active C based materials with compound structure (CFC) the task is much more complicated and need very careful investigations
10
0 2 4 6 8 1010-3
10-2
10-1
100
101 200 eV D plasma CFC NB31 2x1024 Dm2
Texp
= 463 K T
exp = 673 K
Texp
= 773 K T
exp = 948 K
D c
once
ntra
tion
[at
]
Depth [m]
0( ) [1 erf( )]2
xC x C
Dt
Migration in the bulk obeys diffusion equation with D=D(Fluence Temp)
10 15 20 25 3010-17
10-15
10-13
10-11
10-9
10-7
NB31 200 eV D plasma (Magnetron)
Coe
ffici
ent o
f D m
igra
tion
[m2 s
]
1000Temperature [K-1]
LA Sedano et al (1998) NB11 Matrix N11 Matrix NB11 Fibres N11 Fibres
Values for the deuterium migration derived from the D depth profiles are in good agreement with data for intrinsic hydrogen diffusivity in the fibres Migration through pores along fibres with low activation energy may be considered as mechanism of deuterium penetration into the bulk of the CFC materials
Channels of D transport in CFC VAlimov et al
11
Fine grain graphite (as well as CFC) ndashtransparent for gases in principle
Penetrating gas flow via gas pressure for MPG-8 graphite (thickness 126 mm diameter 305 mm)
room temperature
Measured gas flux density j ~ σ P σ Ad
P ndashpressure A ndasharea d- thickness σ ndash specific gas permeability
σ = 5middot1015 mols for MPG-8
Flu
x m
ols
Pressure Pa
Graphite sheet behaves as capillary A=1m2 d =1cm P =1Pa 35middot1017 D2s
12
Influence of tokamak T-10 exposure on MPG-8 graphite permeability
MPG-8 membrane 18 mm thick cut off T-10 limiter demonstrated hydrogen permeability ~9middot1015 molmiddotc-1m-1Pa-1 - 2 times more than for ldquovirginrdquo graphite
Possible reason ndash graphite porosity increase after long term expose in tokamak
All attempts to increase MPG-8 permeability in lab plasma experiments failed
4 mm
Place of limiter tile used for the membrane
14
Comparison of lab experiments and tokamak exposed tile retention in CFC
TDS investigation of the samples CFC N11 implanted by deuterium ions in the laboratory setups (MEPhI) and high field side tile of Tore Supra
[1] Begrambekov L Brosset C Bucalossi J Delchambre E Gunn JP Grisolia C Lipa M Loarer T Mitteau R PMoner-Garbet P Pascal J-Y PShigin P Titov N Tsitrone E Vergazov S Zakharov A ldquoSurface modification and hydrogen isotope retention in CFC during plasma irradiation in the Tore Supra tokamakrdquo17th Internal Conference on Plasma Surface Interactions in Controlled Fusion Devices (PSI17) Hefei China May 22 ndash 26 2006
LABORATORY SAMPLE
TORE SUPRA TILE [1]
Particles deuterons deuterons
Ion energy 50 100 200
500 eV
10-100 eV (as well as low energy atoms molecules and charge exchange neutrals )
Ion flux density 1times1020 atm2s (1-2)times1019 atm2s
Fluence 5times1023 atm2 5times1023 atm2 (estimated)
Surface temperature 450-470 K up to 500-600 K
Retention ~07times1021 atm2 ~2times1022 atm2 (30 times higher)
15
Hydrogen retention via fluence in lab exp
1021 1022 1023 1024 10251020
1021
1022
Hyd
roge
n re
tent
ion
at
m2
Fluence atm2
B4C 100 eVH MPG-8 100 eVH MPG-8 1 keVH HPG99 1 keVH [1] HOPG 100 eVH HOPG 1 keVH
Ion flux density = 35x1020 at(secm2)
[2] L Begrambekov O Buzhinsky A Gordeev E Miljaeva P Leikin P Shigin TDS investigation of hydrogen retention in graphites and carbon based materials Physica scripta N108 (2004) p72-75
Possible underestimation of tokamak tile irradiation fluence hardly could seriously influence the presented data -hydrogen retention will not increase 30 times even for ~100 times higher fluence
16
Possible mechanisms of enhanced D
trapping under tokamak plasma irradiation
1 Presence of hydrogen in the Tore Supra tiles
TDS spectra of H2 and D2 for the as prepared CFC N11 samples irradiated in deuterium plasma
Ei = 100 eVat
Ji = 121020 atm2s
Ф = 451023 atm2
Presence of hydrogen in the CFC twice increases deuterium trapping at the expense of filling the hydrogen traps by deuterium due to isotope
exchange mechanism
Lab experiment
17
2 Trapping of deuterium activated by electron irradiation
[ Collaboration DRFC CEA-Cadarache ndash MEPhI ROSATOM 2007]
Thermal desorption of deuterium as D2
and as CD4 from CFC graphite under
ion and electron irradiationEi=100 eVat Ji=121020 atm2s
Ф=451023 atm2
Increase of deuterium retention along with irradiation time as well as deuterium retention under electron irradiation support an assumption about participation of D2
molecules from surrounding atmosphere in deuterium trapping into graphites Ion and electron irradiation act as a driving forces of the process
Plasma electron irradiation of CFC increased deuterium trapping 12 ndash 3 times depending on energy distribution of impinging deuterium particles
0 200 400 600 800 100000
05
10
15
Ret
entio
n x
1017
at
cm2
Energy eVat
CFC D2 (1020)
D2 electron irr
CFC D2 (2x1019)
electronirradiation
18
3 Transportation of deuterium into the material and trapping in the bulk of the tile
TDS analysis of the samples cut from different depth of the tile shows that more 10 of cumulative trapping collected in the bulk of tile
The samples of 1 ndash 2 mm thickness are usually used in the laboratory experiments The laboratory results could be compared
only to trapping in surface region of tokamak tile
4 Deuterium trapping in graphites irradiated by ion flux with wide energy distribution
Peculiarities of deuterium trapping in graphites exposed to plasma allows to expect an enhancement of retention in graphites irradiated by ion flux with wide energy distribution in tokamaks in comparison with graphites subjected to mono energy ion irradiation in laboratory
setups
19
5 Graphite surface irradiation during Helium Glow Discharge Conditioning
Helium ion bombardment leads to development of the surface relief and destruction of near surface layer As result trapping of deuterium during tokamak discharges should be enhanced
6 Graphite surface irradiation by oxygen impurities
Graphite irradiation by ions and atoms of oxygen impurities leads to accelerated surface destruction and develop the surface As a result trapping of deuterium ions and neutrals by graphite surface is probably more enhanced
20
Conclusion
bull The long range D retention in general is the very complicated physical (amp chemical) problem Many observed features of this phenomenon is not clear now
bull Complex and multiple-factor impact of PFM in tokamaks makes difficult distinguishing its influence on the LR hydrogen isotopes retention
bull Laboratory experiments with well defined impact parameters are crucially necessary
bull During last two years we mounted and calibrated a series of high vacuum installations with well controlled parameters for measurement of D retention in plasma exposed (as well in situ in simulators) samples and started comparative studies of samples radiated at different tokamaks and laboratory installations
21
Plansbull Investigations of samples irradiated in LENTA PR-2
PIN laboratory plasma facilities as well as in T-10 TEXTOR and Tore Supra tokamaks are now in progress
bull As there is very large scattering of the experimental data
on D retention careful measurements at D retention via fluxes (at high fluxes) and temperature in different irradiation facilities are under way
bull To pick up contribution of different factors on D retention step by step experimental investigations at varying definite factors (im flux density consequent and simultaneous irradiation with deuterium and helium broad energy spectra influence etc) are planned
bull Experimental measurements of neutron irradiation influence on hydrogen isotopes retention in PFM is now discussed
- Slide 1
- Slide 2
- Slide 3
- Slide 4
- Slide 5
- Slide 6
- Slide 7
- Slide 8
- Slide 9
- Slide 10
- Slide 11
- Slide 12
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- Slide 21
-
10
0 2 4 6 8 1010-3
10-2
10-1
100
101 200 eV D plasma CFC NB31 2x1024 Dm2
Texp
= 463 K T
exp = 673 K
Texp
= 773 K T
exp = 948 K
D c
once
ntra
tion
[at
]
Depth [m]
0( ) [1 erf( )]2
xC x C
Dt
Migration in the bulk obeys diffusion equation with D=D(Fluence Temp)
10 15 20 25 3010-17
10-15
10-13
10-11
10-9
10-7
NB31 200 eV D plasma (Magnetron)
Coe
ffici
ent o
f D m
igra
tion
[m2 s
]
1000Temperature [K-1]
LA Sedano et al (1998) NB11 Matrix N11 Matrix NB11 Fibres N11 Fibres
Values for the deuterium migration derived from the D depth profiles are in good agreement with data for intrinsic hydrogen diffusivity in the fibres Migration through pores along fibres with low activation energy may be considered as mechanism of deuterium penetration into the bulk of the CFC materials
Channels of D transport in CFC VAlimov et al
11
Fine grain graphite (as well as CFC) ndashtransparent for gases in principle
Penetrating gas flow via gas pressure for MPG-8 graphite (thickness 126 mm diameter 305 mm)
room temperature
Measured gas flux density j ~ σ P σ Ad
P ndashpressure A ndasharea d- thickness σ ndash specific gas permeability
σ = 5middot1015 mols for MPG-8
Flu
x m
ols
Pressure Pa
Graphite sheet behaves as capillary A=1m2 d =1cm P =1Pa 35middot1017 D2s
12
Influence of tokamak T-10 exposure on MPG-8 graphite permeability
MPG-8 membrane 18 mm thick cut off T-10 limiter demonstrated hydrogen permeability ~9middot1015 molmiddotc-1m-1Pa-1 - 2 times more than for ldquovirginrdquo graphite
Possible reason ndash graphite porosity increase after long term expose in tokamak
All attempts to increase MPG-8 permeability in lab plasma experiments failed
4 mm
Place of limiter tile used for the membrane
14
Comparison of lab experiments and tokamak exposed tile retention in CFC
TDS investigation of the samples CFC N11 implanted by deuterium ions in the laboratory setups (MEPhI) and high field side tile of Tore Supra
[1] Begrambekov L Brosset C Bucalossi J Delchambre E Gunn JP Grisolia C Lipa M Loarer T Mitteau R PMoner-Garbet P Pascal J-Y PShigin P Titov N Tsitrone E Vergazov S Zakharov A ldquoSurface modification and hydrogen isotope retention in CFC during plasma irradiation in the Tore Supra tokamakrdquo17th Internal Conference on Plasma Surface Interactions in Controlled Fusion Devices (PSI17) Hefei China May 22 ndash 26 2006
LABORATORY SAMPLE
TORE SUPRA TILE [1]
Particles deuterons deuterons
Ion energy 50 100 200
500 eV
10-100 eV (as well as low energy atoms molecules and charge exchange neutrals )
Ion flux density 1times1020 atm2s (1-2)times1019 atm2s
Fluence 5times1023 atm2 5times1023 atm2 (estimated)
Surface temperature 450-470 K up to 500-600 K
Retention ~07times1021 atm2 ~2times1022 atm2 (30 times higher)
15
Hydrogen retention via fluence in lab exp
1021 1022 1023 1024 10251020
1021
1022
Hyd
roge
n re
tent
ion
at
m2
Fluence atm2
B4C 100 eVH MPG-8 100 eVH MPG-8 1 keVH HPG99 1 keVH [1] HOPG 100 eVH HOPG 1 keVH
Ion flux density = 35x1020 at(secm2)
[2] L Begrambekov O Buzhinsky A Gordeev E Miljaeva P Leikin P Shigin TDS investigation of hydrogen retention in graphites and carbon based materials Physica scripta N108 (2004) p72-75
Possible underestimation of tokamak tile irradiation fluence hardly could seriously influence the presented data -hydrogen retention will not increase 30 times even for ~100 times higher fluence
16
Possible mechanisms of enhanced D
trapping under tokamak plasma irradiation
1 Presence of hydrogen in the Tore Supra tiles
TDS spectra of H2 and D2 for the as prepared CFC N11 samples irradiated in deuterium plasma
Ei = 100 eVat
Ji = 121020 atm2s
Ф = 451023 atm2
Presence of hydrogen in the CFC twice increases deuterium trapping at the expense of filling the hydrogen traps by deuterium due to isotope
exchange mechanism
Lab experiment
17
2 Trapping of deuterium activated by electron irradiation
[ Collaboration DRFC CEA-Cadarache ndash MEPhI ROSATOM 2007]
Thermal desorption of deuterium as D2
and as CD4 from CFC graphite under
ion and electron irradiationEi=100 eVat Ji=121020 atm2s
Ф=451023 atm2
Increase of deuterium retention along with irradiation time as well as deuterium retention under electron irradiation support an assumption about participation of D2
molecules from surrounding atmosphere in deuterium trapping into graphites Ion and electron irradiation act as a driving forces of the process
Plasma electron irradiation of CFC increased deuterium trapping 12 ndash 3 times depending on energy distribution of impinging deuterium particles
0 200 400 600 800 100000
05
10
15
Ret
entio
n x
1017
at
cm2
Energy eVat
CFC D2 (1020)
D2 electron irr
CFC D2 (2x1019)
electronirradiation
18
3 Transportation of deuterium into the material and trapping in the bulk of the tile
TDS analysis of the samples cut from different depth of the tile shows that more 10 of cumulative trapping collected in the bulk of tile
The samples of 1 ndash 2 mm thickness are usually used in the laboratory experiments The laboratory results could be compared
only to trapping in surface region of tokamak tile
4 Deuterium trapping in graphites irradiated by ion flux with wide energy distribution
Peculiarities of deuterium trapping in graphites exposed to plasma allows to expect an enhancement of retention in graphites irradiated by ion flux with wide energy distribution in tokamaks in comparison with graphites subjected to mono energy ion irradiation in laboratory
setups
19
5 Graphite surface irradiation during Helium Glow Discharge Conditioning
Helium ion bombardment leads to development of the surface relief and destruction of near surface layer As result trapping of deuterium during tokamak discharges should be enhanced
6 Graphite surface irradiation by oxygen impurities
Graphite irradiation by ions and atoms of oxygen impurities leads to accelerated surface destruction and develop the surface As a result trapping of deuterium ions and neutrals by graphite surface is probably more enhanced
20
Conclusion
bull The long range D retention in general is the very complicated physical (amp chemical) problem Many observed features of this phenomenon is not clear now
bull Complex and multiple-factor impact of PFM in tokamaks makes difficult distinguishing its influence on the LR hydrogen isotopes retention
bull Laboratory experiments with well defined impact parameters are crucially necessary
bull During last two years we mounted and calibrated a series of high vacuum installations with well controlled parameters for measurement of D retention in plasma exposed (as well in situ in simulators) samples and started comparative studies of samples radiated at different tokamaks and laboratory installations
21
Plansbull Investigations of samples irradiated in LENTA PR-2
PIN laboratory plasma facilities as well as in T-10 TEXTOR and Tore Supra tokamaks are now in progress
bull As there is very large scattering of the experimental data
on D retention careful measurements at D retention via fluxes (at high fluxes) and temperature in different irradiation facilities are under way
bull To pick up contribution of different factors on D retention step by step experimental investigations at varying definite factors (im flux density consequent and simultaneous irradiation with deuterium and helium broad energy spectra influence etc) are planned
bull Experimental measurements of neutron irradiation influence on hydrogen isotopes retention in PFM is now discussed
- Slide 1
- Slide 2
- Slide 3
- Slide 4
- Slide 5
- Slide 6
- Slide 7
- Slide 8
- Slide 9
- Slide 10
- Slide 11
- Slide 12
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- Slide 21
-
11
Fine grain graphite (as well as CFC) ndashtransparent for gases in principle
Penetrating gas flow via gas pressure for MPG-8 graphite (thickness 126 mm diameter 305 mm)
room temperature
Measured gas flux density j ~ σ P σ Ad
P ndashpressure A ndasharea d- thickness σ ndash specific gas permeability
σ = 5middot1015 mols for MPG-8
Flu
x m
ols
Pressure Pa
Graphite sheet behaves as capillary A=1m2 d =1cm P =1Pa 35middot1017 D2s
12
Influence of tokamak T-10 exposure on MPG-8 graphite permeability
MPG-8 membrane 18 mm thick cut off T-10 limiter demonstrated hydrogen permeability ~9middot1015 molmiddotc-1m-1Pa-1 - 2 times more than for ldquovirginrdquo graphite
Possible reason ndash graphite porosity increase after long term expose in tokamak
All attempts to increase MPG-8 permeability in lab plasma experiments failed
4 mm
Place of limiter tile used for the membrane
14
Comparison of lab experiments and tokamak exposed tile retention in CFC
TDS investigation of the samples CFC N11 implanted by deuterium ions in the laboratory setups (MEPhI) and high field side tile of Tore Supra
[1] Begrambekov L Brosset C Bucalossi J Delchambre E Gunn JP Grisolia C Lipa M Loarer T Mitteau R PMoner-Garbet P Pascal J-Y PShigin P Titov N Tsitrone E Vergazov S Zakharov A ldquoSurface modification and hydrogen isotope retention in CFC during plasma irradiation in the Tore Supra tokamakrdquo17th Internal Conference on Plasma Surface Interactions in Controlled Fusion Devices (PSI17) Hefei China May 22 ndash 26 2006
LABORATORY SAMPLE
TORE SUPRA TILE [1]
Particles deuterons deuterons
Ion energy 50 100 200
500 eV
10-100 eV (as well as low energy atoms molecules and charge exchange neutrals )
Ion flux density 1times1020 atm2s (1-2)times1019 atm2s
Fluence 5times1023 atm2 5times1023 atm2 (estimated)
Surface temperature 450-470 K up to 500-600 K
Retention ~07times1021 atm2 ~2times1022 atm2 (30 times higher)
15
Hydrogen retention via fluence in lab exp
1021 1022 1023 1024 10251020
1021
1022
Hyd
roge
n re
tent
ion
at
m2
Fluence atm2
B4C 100 eVH MPG-8 100 eVH MPG-8 1 keVH HPG99 1 keVH [1] HOPG 100 eVH HOPG 1 keVH
Ion flux density = 35x1020 at(secm2)
[2] L Begrambekov O Buzhinsky A Gordeev E Miljaeva P Leikin P Shigin TDS investigation of hydrogen retention in graphites and carbon based materials Physica scripta N108 (2004) p72-75
Possible underestimation of tokamak tile irradiation fluence hardly could seriously influence the presented data -hydrogen retention will not increase 30 times even for ~100 times higher fluence
16
Possible mechanisms of enhanced D
trapping under tokamak plasma irradiation
1 Presence of hydrogen in the Tore Supra tiles
TDS spectra of H2 and D2 for the as prepared CFC N11 samples irradiated in deuterium plasma
Ei = 100 eVat
Ji = 121020 atm2s
Ф = 451023 atm2
Presence of hydrogen in the CFC twice increases deuterium trapping at the expense of filling the hydrogen traps by deuterium due to isotope
exchange mechanism
Lab experiment
17
2 Trapping of deuterium activated by electron irradiation
[ Collaboration DRFC CEA-Cadarache ndash MEPhI ROSATOM 2007]
Thermal desorption of deuterium as D2
and as CD4 from CFC graphite under
ion and electron irradiationEi=100 eVat Ji=121020 atm2s
Ф=451023 atm2
Increase of deuterium retention along with irradiation time as well as deuterium retention under electron irradiation support an assumption about participation of D2
molecules from surrounding atmosphere in deuterium trapping into graphites Ion and electron irradiation act as a driving forces of the process
Plasma electron irradiation of CFC increased deuterium trapping 12 ndash 3 times depending on energy distribution of impinging deuterium particles
0 200 400 600 800 100000
05
10
15
Ret
entio
n x
1017
at
cm2
Energy eVat
CFC D2 (1020)
D2 electron irr
CFC D2 (2x1019)
electronirradiation
18
3 Transportation of deuterium into the material and trapping in the bulk of the tile
TDS analysis of the samples cut from different depth of the tile shows that more 10 of cumulative trapping collected in the bulk of tile
The samples of 1 ndash 2 mm thickness are usually used in the laboratory experiments The laboratory results could be compared
only to trapping in surface region of tokamak tile
4 Deuterium trapping in graphites irradiated by ion flux with wide energy distribution
Peculiarities of deuterium trapping in graphites exposed to plasma allows to expect an enhancement of retention in graphites irradiated by ion flux with wide energy distribution in tokamaks in comparison with graphites subjected to mono energy ion irradiation in laboratory
setups
19
5 Graphite surface irradiation during Helium Glow Discharge Conditioning
Helium ion bombardment leads to development of the surface relief and destruction of near surface layer As result trapping of deuterium during tokamak discharges should be enhanced
6 Graphite surface irradiation by oxygen impurities
Graphite irradiation by ions and atoms of oxygen impurities leads to accelerated surface destruction and develop the surface As a result trapping of deuterium ions and neutrals by graphite surface is probably more enhanced
20
Conclusion
bull The long range D retention in general is the very complicated physical (amp chemical) problem Many observed features of this phenomenon is not clear now
bull Complex and multiple-factor impact of PFM in tokamaks makes difficult distinguishing its influence on the LR hydrogen isotopes retention
bull Laboratory experiments with well defined impact parameters are crucially necessary
bull During last two years we mounted and calibrated a series of high vacuum installations with well controlled parameters for measurement of D retention in plasma exposed (as well in situ in simulators) samples and started comparative studies of samples radiated at different tokamaks and laboratory installations
21
Plansbull Investigations of samples irradiated in LENTA PR-2
PIN laboratory plasma facilities as well as in T-10 TEXTOR and Tore Supra tokamaks are now in progress
bull As there is very large scattering of the experimental data
on D retention careful measurements at D retention via fluxes (at high fluxes) and temperature in different irradiation facilities are under way
bull To pick up contribution of different factors on D retention step by step experimental investigations at varying definite factors (im flux density consequent and simultaneous irradiation with deuterium and helium broad energy spectra influence etc) are planned
bull Experimental measurements of neutron irradiation influence on hydrogen isotopes retention in PFM is now discussed
- Slide 1
- Slide 2
- Slide 3
- Slide 4
- Slide 5
- Slide 6
- Slide 7
- Slide 8
- Slide 9
- Slide 10
- Slide 11
- Slide 12
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- Slide 21
-
12
Influence of tokamak T-10 exposure on MPG-8 graphite permeability
MPG-8 membrane 18 mm thick cut off T-10 limiter demonstrated hydrogen permeability ~9middot1015 molmiddotc-1m-1Pa-1 - 2 times more than for ldquovirginrdquo graphite
Possible reason ndash graphite porosity increase after long term expose in tokamak
All attempts to increase MPG-8 permeability in lab plasma experiments failed
4 mm
Place of limiter tile used for the membrane
14
Comparison of lab experiments and tokamak exposed tile retention in CFC
TDS investigation of the samples CFC N11 implanted by deuterium ions in the laboratory setups (MEPhI) and high field side tile of Tore Supra
[1] Begrambekov L Brosset C Bucalossi J Delchambre E Gunn JP Grisolia C Lipa M Loarer T Mitteau R PMoner-Garbet P Pascal J-Y PShigin P Titov N Tsitrone E Vergazov S Zakharov A ldquoSurface modification and hydrogen isotope retention in CFC during plasma irradiation in the Tore Supra tokamakrdquo17th Internal Conference on Plasma Surface Interactions in Controlled Fusion Devices (PSI17) Hefei China May 22 ndash 26 2006
LABORATORY SAMPLE
TORE SUPRA TILE [1]
Particles deuterons deuterons
Ion energy 50 100 200
500 eV
10-100 eV (as well as low energy atoms molecules and charge exchange neutrals )
Ion flux density 1times1020 atm2s (1-2)times1019 atm2s
Fluence 5times1023 atm2 5times1023 atm2 (estimated)
Surface temperature 450-470 K up to 500-600 K
Retention ~07times1021 atm2 ~2times1022 atm2 (30 times higher)
15
Hydrogen retention via fluence in lab exp
1021 1022 1023 1024 10251020
1021
1022
Hyd
roge
n re
tent
ion
at
m2
Fluence atm2
B4C 100 eVH MPG-8 100 eVH MPG-8 1 keVH HPG99 1 keVH [1] HOPG 100 eVH HOPG 1 keVH
Ion flux density = 35x1020 at(secm2)
[2] L Begrambekov O Buzhinsky A Gordeev E Miljaeva P Leikin P Shigin TDS investigation of hydrogen retention in graphites and carbon based materials Physica scripta N108 (2004) p72-75
Possible underestimation of tokamak tile irradiation fluence hardly could seriously influence the presented data -hydrogen retention will not increase 30 times even for ~100 times higher fluence
16
Possible mechanisms of enhanced D
trapping under tokamak plasma irradiation
1 Presence of hydrogen in the Tore Supra tiles
TDS spectra of H2 and D2 for the as prepared CFC N11 samples irradiated in deuterium plasma
Ei = 100 eVat
Ji = 121020 atm2s
Ф = 451023 atm2
Presence of hydrogen in the CFC twice increases deuterium trapping at the expense of filling the hydrogen traps by deuterium due to isotope
exchange mechanism
Lab experiment
17
2 Trapping of deuterium activated by electron irradiation
[ Collaboration DRFC CEA-Cadarache ndash MEPhI ROSATOM 2007]
Thermal desorption of deuterium as D2
and as CD4 from CFC graphite under
ion and electron irradiationEi=100 eVat Ji=121020 atm2s
Ф=451023 atm2
Increase of deuterium retention along with irradiation time as well as deuterium retention under electron irradiation support an assumption about participation of D2
molecules from surrounding atmosphere in deuterium trapping into graphites Ion and electron irradiation act as a driving forces of the process
Plasma electron irradiation of CFC increased deuterium trapping 12 ndash 3 times depending on energy distribution of impinging deuterium particles
0 200 400 600 800 100000
05
10
15
Ret
entio
n x
1017
at
cm2
Energy eVat
CFC D2 (1020)
D2 electron irr
CFC D2 (2x1019)
electronirradiation
18
3 Transportation of deuterium into the material and trapping in the bulk of the tile
TDS analysis of the samples cut from different depth of the tile shows that more 10 of cumulative trapping collected in the bulk of tile
The samples of 1 ndash 2 mm thickness are usually used in the laboratory experiments The laboratory results could be compared
only to trapping in surface region of tokamak tile
4 Deuterium trapping in graphites irradiated by ion flux with wide energy distribution
Peculiarities of deuterium trapping in graphites exposed to plasma allows to expect an enhancement of retention in graphites irradiated by ion flux with wide energy distribution in tokamaks in comparison with graphites subjected to mono energy ion irradiation in laboratory
setups
19
5 Graphite surface irradiation during Helium Glow Discharge Conditioning
Helium ion bombardment leads to development of the surface relief and destruction of near surface layer As result trapping of deuterium during tokamak discharges should be enhanced
6 Graphite surface irradiation by oxygen impurities
Graphite irradiation by ions and atoms of oxygen impurities leads to accelerated surface destruction and develop the surface As a result trapping of deuterium ions and neutrals by graphite surface is probably more enhanced
20
Conclusion
bull The long range D retention in general is the very complicated physical (amp chemical) problem Many observed features of this phenomenon is not clear now
bull Complex and multiple-factor impact of PFM in tokamaks makes difficult distinguishing its influence on the LR hydrogen isotopes retention
bull Laboratory experiments with well defined impact parameters are crucially necessary
bull During last two years we mounted and calibrated a series of high vacuum installations with well controlled parameters for measurement of D retention in plasma exposed (as well in situ in simulators) samples and started comparative studies of samples radiated at different tokamaks and laboratory installations
21
Plansbull Investigations of samples irradiated in LENTA PR-2
PIN laboratory plasma facilities as well as in T-10 TEXTOR and Tore Supra tokamaks are now in progress
bull As there is very large scattering of the experimental data
on D retention careful measurements at D retention via fluxes (at high fluxes) and temperature in different irradiation facilities are under way
bull To pick up contribution of different factors on D retention step by step experimental investigations at varying definite factors (im flux density consequent and simultaneous irradiation with deuterium and helium broad energy spectra influence etc) are planned
bull Experimental measurements of neutron irradiation influence on hydrogen isotopes retention in PFM is now discussed
- Slide 1
- Slide 2
- Slide 3
- Slide 4
- Slide 5
- Slide 6
- Slide 7
- Slide 8
- Slide 9
- Slide 10
- Slide 11
- Slide 12
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- Slide 21
-
14
Comparison of lab experiments and tokamak exposed tile retention in CFC
TDS investigation of the samples CFC N11 implanted by deuterium ions in the laboratory setups (MEPhI) and high field side tile of Tore Supra
[1] Begrambekov L Brosset C Bucalossi J Delchambre E Gunn JP Grisolia C Lipa M Loarer T Mitteau R PMoner-Garbet P Pascal J-Y PShigin P Titov N Tsitrone E Vergazov S Zakharov A ldquoSurface modification and hydrogen isotope retention in CFC during plasma irradiation in the Tore Supra tokamakrdquo17th Internal Conference on Plasma Surface Interactions in Controlled Fusion Devices (PSI17) Hefei China May 22 ndash 26 2006
LABORATORY SAMPLE
TORE SUPRA TILE [1]
Particles deuterons deuterons
Ion energy 50 100 200
500 eV
10-100 eV (as well as low energy atoms molecules and charge exchange neutrals )
Ion flux density 1times1020 atm2s (1-2)times1019 atm2s
Fluence 5times1023 atm2 5times1023 atm2 (estimated)
Surface temperature 450-470 K up to 500-600 K
Retention ~07times1021 atm2 ~2times1022 atm2 (30 times higher)
15
Hydrogen retention via fluence in lab exp
1021 1022 1023 1024 10251020
1021
1022
Hyd
roge
n re
tent
ion
at
m2
Fluence atm2
B4C 100 eVH MPG-8 100 eVH MPG-8 1 keVH HPG99 1 keVH [1] HOPG 100 eVH HOPG 1 keVH
Ion flux density = 35x1020 at(secm2)
[2] L Begrambekov O Buzhinsky A Gordeev E Miljaeva P Leikin P Shigin TDS investigation of hydrogen retention in graphites and carbon based materials Physica scripta N108 (2004) p72-75
Possible underestimation of tokamak tile irradiation fluence hardly could seriously influence the presented data -hydrogen retention will not increase 30 times even for ~100 times higher fluence
16
Possible mechanisms of enhanced D
trapping under tokamak plasma irradiation
1 Presence of hydrogen in the Tore Supra tiles
TDS spectra of H2 and D2 for the as prepared CFC N11 samples irradiated in deuterium plasma
Ei = 100 eVat
Ji = 121020 atm2s
Ф = 451023 atm2
Presence of hydrogen in the CFC twice increases deuterium trapping at the expense of filling the hydrogen traps by deuterium due to isotope
exchange mechanism
Lab experiment
17
2 Trapping of deuterium activated by electron irradiation
[ Collaboration DRFC CEA-Cadarache ndash MEPhI ROSATOM 2007]
Thermal desorption of deuterium as D2
and as CD4 from CFC graphite under
ion and electron irradiationEi=100 eVat Ji=121020 atm2s
Ф=451023 atm2
Increase of deuterium retention along with irradiation time as well as deuterium retention under electron irradiation support an assumption about participation of D2
molecules from surrounding atmosphere in deuterium trapping into graphites Ion and electron irradiation act as a driving forces of the process
Plasma electron irradiation of CFC increased deuterium trapping 12 ndash 3 times depending on energy distribution of impinging deuterium particles
0 200 400 600 800 100000
05
10
15
Ret
entio
n x
1017
at
cm2
Energy eVat
CFC D2 (1020)
D2 electron irr
CFC D2 (2x1019)
electronirradiation
18
3 Transportation of deuterium into the material and trapping in the bulk of the tile
TDS analysis of the samples cut from different depth of the tile shows that more 10 of cumulative trapping collected in the bulk of tile
The samples of 1 ndash 2 mm thickness are usually used in the laboratory experiments The laboratory results could be compared
only to trapping in surface region of tokamak tile
4 Deuterium trapping in graphites irradiated by ion flux with wide energy distribution
Peculiarities of deuterium trapping in graphites exposed to plasma allows to expect an enhancement of retention in graphites irradiated by ion flux with wide energy distribution in tokamaks in comparison with graphites subjected to mono energy ion irradiation in laboratory
setups
19
5 Graphite surface irradiation during Helium Glow Discharge Conditioning
Helium ion bombardment leads to development of the surface relief and destruction of near surface layer As result trapping of deuterium during tokamak discharges should be enhanced
6 Graphite surface irradiation by oxygen impurities
Graphite irradiation by ions and atoms of oxygen impurities leads to accelerated surface destruction and develop the surface As a result trapping of deuterium ions and neutrals by graphite surface is probably more enhanced
20
Conclusion
bull The long range D retention in general is the very complicated physical (amp chemical) problem Many observed features of this phenomenon is not clear now
bull Complex and multiple-factor impact of PFM in tokamaks makes difficult distinguishing its influence on the LR hydrogen isotopes retention
bull Laboratory experiments with well defined impact parameters are crucially necessary
bull During last two years we mounted and calibrated a series of high vacuum installations with well controlled parameters for measurement of D retention in plasma exposed (as well in situ in simulators) samples and started comparative studies of samples radiated at different tokamaks and laboratory installations
21
Plansbull Investigations of samples irradiated in LENTA PR-2
PIN laboratory plasma facilities as well as in T-10 TEXTOR and Tore Supra tokamaks are now in progress
bull As there is very large scattering of the experimental data
on D retention careful measurements at D retention via fluxes (at high fluxes) and temperature in different irradiation facilities are under way
bull To pick up contribution of different factors on D retention step by step experimental investigations at varying definite factors (im flux density consequent and simultaneous irradiation with deuterium and helium broad energy spectra influence etc) are planned
bull Experimental measurements of neutron irradiation influence on hydrogen isotopes retention in PFM is now discussed
- Slide 1
- Slide 2
- Slide 3
- Slide 4
- Slide 5
- Slide 6
- Slide 7
- Slide 8
- Slide 9
- Slide 10
- Slide 11
- Slide 12
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- Slide 21
-
15
Hydrogen retention via fluence in lab exp
1021 1022 1023 1024 10251020
1021
1022
Hyd
roge
n re
tent
ion
at
m2
Fluence atm2
B4C 100 eVH MPG-8 100 eVH MPG-8 1 keVH HPG99 1 keVH [1] HOPG 100 eVH HOPG 1 keVH
Ion flux density = 35x1020 at(secm2)
[2] L Begrambekov O Buzhinsky A Gordeev E Miljaeva P Leikin P Shigin TDS investigation of hydrogen retention in graphites and carbon based materials Physica scripta N108 (2004) p72-75
Possible underestimation of tokamak tile irradiation fluence hardly could seriously influence the presented data -hydrogen retention will not increase 30 times even for ~100 times higher fluence
16
Possible mechanisms of enhanced D
trapping under tokamak plasma irradiation
1 Presence of hydrogen in the Tore Supra tiles
TDS spectra of H2 and D2 for the as prepared CFC N11 samples irradiated in deuterium plasma
Ei = 100 eVat
Ji = 121020 atm2s
Ф = 451023 atm2
Presence of hydrogen in the CFC twice increases deuterium trapping at the expense of filling the hydrogen traps by deuterium due to isotope
exchange mechanism
Lab experiment
17
2 Trapping of deuterium activated by electron irradiation
[ Collaboration DRFC CEA-Cadarache ndash MEPhI ROSATOM 2007]
Thermal desorption of deuterium as D2
and as CD4 from CFC graphite under
ion and electron irradiationEi=100 eVat Ji=121020 atm2s
Ф=451023 atm2
Increase of deuterium retention along with irradiation time as well as deuterium retention under electron irradiation support an assumption about participation of D2
molecules from surrounding atmosphere in deuterium trapping into graphites Ion and electron irradiation act as a driving forces of the process
Plasma electron irradiation of CFC increased deuterium trapping 12 ndash 3 times depending on energy distribution of impinging deuterium particles
0 200 400 600 800 100000
05
10
15
Ret
entio
n x
1017
at
cm2
Energy eVat
CFC D2 (1020)
D2 electron irr
CFC D2 (2x1019)
electronirradiation
18
3 Transportation of deuterium into the material and trapping in the bulk of the tile
TDS analysis of the samples cut from different depth of the tile shows that more 10 of cumulative trapping collected in the bulk of tile
The samples of 1 ndash 2 mm thickness are usually used in the laboratory experiments The laboratory results could be compared
only to trapping in surface region of tokamak tile
4 Deuterium trapping in graphites irradiated by ion flux with wide energy distribution
Peculiarities of deuterium trapping in graphites exposed to plasma allows to expect an enhancement of retention in graphites irradiated by ion flux with wide energy distribution in tokamaks in comparison with graphites subjected to mono energy ion irradiation in laboratory
setups
19
5 Graphite surface irradiation during Helium Glow Discharge Conditioning
Helium ion bombardment leads to development of the surface relief and destruction of near surface layer As result trapping of deuterium during tokamak discharges should be enhanced
6 Graphite surface irradiation by oxygen impurities
Graphite irradiation by ions and atoms of oxygen impurities leads to accelerated surface destruction and develop the surface As a result trapping of deuterium ions and neutrals by graphite surface is probably more enhanced
20
Conclusion
bull The long range D retention in general is the very complicated physical (amp chemical) problem Many observed features of this phenomenon is not clear now
bull Complex and multiple-factor impact of PFM in tokamaks makes difficult distinguishing its influence on the LR hydrogen isotopes retention
bull Laboratory experiments with well defined impact parameters are crucially necessary
bull During last two years we mounted and calibrated a series of high vacuum installations with well controlled parameters for measurement of D retention in plasma exposed (as well in situ in simulators) samples and started comparative studies of samples radiated at different tokamaks and laboratory installations
21
Plansbull Investigations of samples irradiated in LENTA PR-2
PIN laboratory plasma facilities as well as in T-10 TEXTOR and Tore Supra tokamaks are now in progress
bull As there is very large scattering of the experimental data
on D retention careful measurements at D retention via fluxes (at high fluxes) and temperature in different irradiation facilities are under way
bull To pick up contribution of different factors on D retention step by step experimental investigations at varying definite factors (im flux density consequent and simultaneous irradiation with deuterium and helium broad energy spectra influence etc) are planned
bull Experimental measurements of neutron irradiation influence on hydrogen isotopes retention in PFM is now discussed
- Slide 1
- Slide 2
- Slide 3
- Slide 4
- Slide 5
- Slide 6
- Slide 7
- Slide 8
- Slide 9
- Slide 10
- Slide 11
- Slide 12
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- Slide 21
-
16
Possible mechanisms of enhanced D
trapping under tokamak plasma irradiation
1 Presence of hydrogen in the Tore Supra tiles
TDS spectra of H2 and D2 for the as prepared CFC N11 samples irradiated in deuterium plasma
Ei = 100 eVat
Ji = 121020 atm2s
Ф = 451023 atm2
Presence of hydrogen in the CFC twice increases deuterium trapping at the expense of filling the hydrogen traps by deuterium due to isotope
exchange mechanism
Lab experiment
17
2 Trapping of deuterium activated by electron irradiation
[ Collaboration DRFC CEA-Cadarache ndash MEPhI ROSATOM 2007]
Thermal desorption of deuterium as D2
and as CD4 from CFC graphite under
ion and electron irradiationEi=100 eVat Ji=121020 atm2s
Ф=451023 atm2
Increase of deuterium retention along with irradiation time as well as deuterium retention under electron irradiation support an assumption about participation of D2
molecules from surrounding atmosphere in deuterium trapping into graphites Ion and electron irradiation act as a driving forces of the process
Plasma electron irradiation of CFC increased deuterium trapping 12 ndash 3 times depending on energy distribution of impinging deuterium particles
0 200 400 600 800 100000
05
10
15
Ret
entio
n x
1017
at
cm2
Energy eVat
CFC D2 (1020)
D2 electron irr
CFC D2 (2x1019)
electronirradiation
18
3 Transportation of deuterium into the material and trapping in the bulk of the tile
TDS analysis of the samples cut from different depth of the tile shows that more 10 of cumulative trapping collected in the bulk of tile
The samples of 1 ndash 2 mm thickness are usually used in the laboratory experiments The laboratory results could be compared
only to trapping in surface region of tokamak tile
4 Deuterium trapping in graphites irradiated by ion flux with wide energy distribution
Peculiarities of deuterium trapping in graphites exposed to plasma allows to expect an enhancement of retention in graphites irradiated by ion flux with wide energy distribution in tokamaks in comparison with graphites subjected to mono energy ion irradiation in laboratory
setups
19
5 Graphite surface irradiation during Helium Glow Discharge Conditioning
Helium ion bombardment leads to development of the surface relief and destruction of near surface layer As result trapping of deuterium during tokamak discharges should be enhanced
6 Graphite surface irradiation by oxygen impurities
Graphite irradiation by ions and atoms of oxygen impurities leads to accelerated surface destruction and develop the surface As a result trapping of deuterium ions and neutrals by graphite surface is probably more enhanced
20
Conclusion
bull The long range D retention in general is the very complicated physical (amp chemical) problem Many observed features of this phenomenon is not clear now
bull Complex and multiple-factor impact of PFM in tokamaks makes difficult distinguishing its influence on the LR hydrogen isotopes retention
bull Laboratory experiments with well defined impact parameters are crucially necessary
bull During last two years we mounted and calibrated a series of high vacuum installations with well controlled parameters for measurement of D retention in plasma exposed (as well in situ in simulators) samples and started comparative studies of samples radiated at different tokamaks and laboratory installations
21
Plansbull Investigations of samples irradiated in LENTA PR-2
PIN laboratory plasma facilities as well as in T-10 TEXTOR and Tore Supra tokamaks are now in progress
bull As there is very large scattering of the experimental data
on D retention careful measurements at D retention via fluxes (at high fluxes) and temperature in different irradiation facilities are under way
bull To pick up contribution of different factors on D retention step by step experimental investigations at varying definite factors (im flux density consequent and simultaneous irradiation with deuterium and helium broad energy spectra influence etc) are planned
bull Experimental measurements of neutron irradiation influence on hydrogen isotopes retention in PFM is now discussed
- Slide 1
- Slide 2
- Slide 3
- Slide 4
- Slide 5
- Slide 6
- Slide 7
- Slide 8
- Slide 9
- Slide 10
- Slide 11
- Slide 12
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- Slide 21
-
17
2 Trapping of deuterium activated by electron irradiation
[ Collaboration DRFC CEA-Cadarache ndash MEPhI ROSATOM 2007]
Thermal desorption of deuterium as D2
and as CD4 from CFC graphite under
ion and electron irradiationEi=100 eVat Ji=121020 atm2s
Ф=451023 atm2
Increase of deuterium retention along with irradiation time as well as deuterium retention under electron irradiation support an assumption about participation of D2
molecules from surrounding atmosphere in deuterium trapping into graphites Ion and electron irradiation act as a driving forces of the process
Plasma electron irradiation of CFC increased deuterium trapping 12 ndash 3 times depending on energy distribution of impinging deuterium particles
0 200 400 600 800 100000
05
10
15
Ret
entio
n x
1017
at
cm2
Energy eVat
CFC D2 (1020)
D2 electron irr
CFC D2 (2x1019)
electronirradiation
18
3 Transportation of deuterium into the material and trapping in the bulk of the tile
TDS analysis of the samples cut from different depth of the tile shows that more 10 of cumulative trapping collected in the bulk of tile
The samples of 1 ndash 2 mm thickness are usually used in the laboratory experiments The laboratory results could be compared
only to trapping in surface region of tokamak tile
4 Deuterium trapping in graphites irradiated by ion flux with wide energy distribution
Peculiarities of deuterium trapping in graphites exposed to plasma allows to expect an enhancement of retention in graphites irradiated by ion flux with wide energy distribution in tokamaks in comparison with graphites subjected to mono energy ion irradiation in laboratory
setups
19
5 Graphite surface irradiation during Helium Glow Discharge Conditioning
Helium ion bombardment leads to development of the surface relief and destruction of near surface layer As result trapping of deuterium during tokamak discharges should be enhanced
6 Graphite surface irradiation by oxygen impurities
Graphite irradiation by ions and atoms of oxygen impurities leads to accelerated surface destruction and develop the surface As a result trapping of deuterium ions and neutrals by graphite surface is probably more enhanced
20
Conclusion
bull The long range D retention in general is the very complicated physical (amp chemical) problem Many observed features of this phenomenon is not clear now
bull Complex and multiple-factor impact of PFM in tokamaks makes difficult distinguishing its influence on the LR hydrogen isotopes retention
bull Laboratory experiments with well defined impact parameters are crucially necessary
bull During last two years we mounted and calibrated a series of high vacuum installations with well controlled parameters for measurement of D retention in plasma exposed (as well in situ in simulators) samples and started comparative studies of samples radiated at different tokamaks and laboratory installations
21
Plansbull Investigations of samples irradiated in LENTA PR-2
PIN laboratory plasma facilities as well as in T-10 TEXTOR and Tore Supra tokamaks are now in progress
bull As there is very large scattering of the experimental data
on D retention careful measurements at D retention via fluxes (at high fluxes) and temperature in different irradiation facilities are under way
bull To pick up contribution of different factors on D retention step by step experimental investigations at varying definite factors (im flux density consequent and simultaneous irradiation with deuterium and helium broad energy spectra influence etc) are planned
bull Experimental measurements of neutron irradiation influence on hydrogen isotopes retention in PFM is now discussed
- Slide 1
- Slide 2
- Slide 3
- Slide 4
- Slide 5
- Slide 6
- Slide 7
- Slide 8
- Slide 9
- Slide 10
- Slide 11
- Slide 12
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- Slide 21
-
18
3 Transportation of deuterium into the material and trapping in the bulk of the tile
TDS analysis of the samples cut from different depth of the tile shows that more 10 of cumulative trapping collected in the bulk of tile
The samples of 1 ndash 2 mm thickness are usually used in the laboratory experiments The laboratory results could be compared
only to trapping in surface region of tokamak tile
4 Deuterium trapping in graphites irradiated by ion flux with wide energy distribution
Peculiarities of deuterium trapping in graphites exposed to plasma allows to expect an enhancement of retention in graphites irradiated by ion flux with wide energy distribution in tokamaks in comparison with graphites subjected to mono energy ion irradiation in laboratory
setups
19
5 Graphite surface irradiation during Helium Glow Discharge Conditioning
Helium ion bombardment leads to development of the surface relief and destruction of near surface layer As result trapping of deuterium during tokamak discharges should be enhanced
6 Graphite surface irradiation by oxygen impurities
Graphite irradiation by ions and atoms of oxygen impurities leads to accelerated surface destruction and develop the surface As a result trapping of deuterium ions and neutrals by graphite surface is probably more enhanced
20
Conclusion
bull The long range D retention in general is the very complicated physical (amp chemical) problem Many observed features of this phenomenon is not clear now
bull Complex and multiple-factor impact of PFM in tokamaks makes difficult distinguishing its influence on the LR hydrogen isotopes retention
bull Laboratory experiments with well defined impact parameters are crucially necessary
bull During last two years we mounted and calibrated a series of high vacuum installations with well controlled parameters for measurement of D retention in plasma exposed (as well in situ in simulators) samples and started comparative studies of samples radiated at different tokamaks and laboratory installations
21
Plansbull Investigations of samples irradiated in LENTA PR-2
PIN laboratory plasma facilities as well as in T-10 TEXTOR and Tore Supra tokamaks are now in progress
bull As there is very large scattering of the experimental data
on D retention careful measurements at D retention via fluxes (at high fluxes) and temperature in different irradiation facilities are under way
bull To pick up contribution of different factors on D retention step by step experimental investigations at varying definite factors (im flux density consequent and simultaneous irradiation with deuterium and helium broad energy spectra influence etc) are planned
bull Experimental measurements of neutron irradiation influence on hydrogen isotopes retention in PFM is now discussed
- Slide 1
- Slide 2
- Slide 3
- Slide 4
- Slide 5
- Slide 6
- Slide 7
- Slide 8
- Slide 9
- Slide 10
- Slide 11
- Slide 12
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- Slide 21
-
19
5 Graphite surface irradiation during Helium Glow Discharge Conditioning
Helium ion bombardment leads to development of the surface relief and destruction of near surface layer As result trapping of deuterium during tokamak discharges should be enhanced
6 Graphite surface irradiation by oxygen impurities
Graphite irradiation by ions and atoms of oxygen impurities leads to accelerated surface destruction and develop the surface As a result trapping of deuterium ions and neutrals by graphite surface is probably more enhanced
20
Conclusion
bull The long range D retention in general is the very complicated physical (amp chemical) problem Many observed features of this phenomenon is not clear now
bull Complex and multiple-factor impact of PFM in tokamaks makes difficult distinguishing its influence on the LR hydrogen isotopes retention
bull Laboratory experiments with well defined impact parameters are crucially necessary
bull During last two years we mounted and calibrated a series of high vacuum installations with well controlled parameters for measurement of D retention in plasma exposed (as well in situ in simulators) samples and started comparative studies of samples radiated at different tokamaks and laboratory installations
21
Plansbull Investigations of samples irradiated in LENTA PR-2
PIN laboratory plasma facilities as well as in T-10 TEXTOR and Tore Supra tokamaks are now in progress
bull As there is very large scattering of the experimental data
on D retention careful measurements at D retention via fluxes (at high fluxes) and temperature in different irradiation facilities are under way
bull To pick up contribution of different factors on D retention step by step experimental investigations at varying definite factors (im flux density consequent and simultaneous irradiation with deuterium and helium broad energy spectra influence etc) are planned
bull Experimental measurements of neutron irradiation influence on hydrogen isotopes retention in PFM is now discussed
- Slide 1
- Slide 2
- Slide 3
- Slide 4
- Slide 5
- Slide 6
- Slide 7
- Slide 8
- Slide 9
- Slide 10
- Slide 11
- Slide 12
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- Slide 21
-
20
Conclusion
bull The long range D retention in general is the very complicated physical (amp chemical) problem Many observed features of this phenomenon is not clear now
bull Complex and multiple-factor impact of PFM in tokamaks makes difficult distinguishing its influence on the LR hydrogen isotopes retention
bull Laboratory experiments with well defined impact parameters are crucially necessary
bull During last two years we mounted and calibrated a series of high vacuum installations with well controlled parameters for measurement of D retention in plasma exposed (as well in situ in simulators) samples and started comparative studies of samples radiated at different tokamaks and laboratory installations
21
Plansbull Investigations of samples irradiated in LENTA PR-2
PIN laboratory plasma facilities as well as in T-10 TEXTOR and Tore Supra tokamaks are now in progress
bull As there is very large scattering of the experimental data
on D retention careful measurements at D retention via fluxes (at high fluxes) and temperature in different irradiation facilities are under way
bull To pick up contribution of different factors on D retention step by step experimental investigations at varying definite factors (im flux density consequent and simultaneous irradiation with deuterium and helium broad energy spectra influence etc) are planned
bull Experimental measurements of neutron irradiation influence on hydrogen isotopes retention in PFM is now discussed
- Slide 1
- Slide 2
- Slide 3
- Slide 4
- Slide 5
- Slide 6
- Slide 7
- Slide 8
- Slide 9
- Slide 10
- Slide 11
- Slide 12
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- Slide 21
-
21
Plansbull Investigations of samples irradiated in LENTA PR-2
PIN laboratory plasma facilities as well as in T-10 TEXTOR and Tore Supra tokamaks are now in progress
bull As there is very large scattering of the experimental data
on D retention careful measurements at D retention via fluxes (at high fluxes) and temperature in different irradiation facilities are under way
bull To pick up contribution of different factors on D retention step by step experimental investigations at varying definite factors (im flux density consequent and simultaneous irradiation with deuterium and helium broad energy spectra influence etc) are planned
bull Experimental measurements of neutron irradiation influence on hydrogen isotopes retention in PFM is now discussed
- Slide 1
- Slide 2
- Slide 3
- Slide 4
- Slide 5
- Slide 6
- Slide 7
- Slide 8
- Slide 9
- Slide 10
- Slide 11
- Slide 12
- Slide 14
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- Slide 21
-