deuterium retention in and release from beryllium ... · deuterium retention in and release from...
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D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
Deuterium Retention in and Release from Beryllium Resulting
from High Flux Plasma Exposure
aMax-Planck-Institut für Plasmaphysik, 85748 Garching, GermanybGeneral Atomics, San Diego, CA 92121, USA
cUniversity of California San Diego, CA 92093, USA
T. Schwarz-Selingera, M. Oberkoflera, H. Xub
R. Doernerc and the PISCES Teamc
Max-Planck-Institutfür Plasmaphysik
13th International Workshop on Plasma-Facing Materials and Components for Fusion Applications /
1st International Conference on Fusion Energy Materials Science
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
Motivation: T Removal in ITER
T Retention in pure Beryllium
implantation: saturation at low levels
codeposition: unlimited
main wall erosion dominated, but:
- gaps are potential deposition zones!
- resessed wall elements
assessing T removal by baking at
240°C / 350°C
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
K. Sugiyama et al., PSI-19(doi:10.1016/j.jnucmat.2010.09.043):
ITER baking temperatures 240ºC (main wall) 350ºC (divertor)
assessment of T removal in ITER by wall baking
Here: thick codeposits is removal efficiency increased for longer hold times?
(is release determined by diffusion or by trap/bond energies)
0 2000 40001E-3
0.01
0.1
1
100
200
300
400
500
600
D fl
ux (1
015 D
cm
-2s-1
)
time (sec)
0.3
K/se
c
ramp tem
perature (°C)
600 eV D3+ implanted in 300 nm thick
TVA deposited Be layers
350°C
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
outline
Deuterium Retention in and Release from Beryllium Resulting
from High Flux Plasma Exposure
D release from thick codeposits for long hold times at 240°C / 350°C
single / multilayer co-deposits
high flux codeposit
implanted Be
model system: magnetron sputtered D/Be
Comparing D release from
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
PISCES-B
W witness plate
B fieldBe target
optionalBe
seeding
target:bias: < -170V results in E < 150eV+ high flux:D ion flux: < 5·1018 cm-2s-1
Be seeding: nBe/nD < 3% - one sample at a time- implantation profile
witness plate:energy of sputtered Be: few eVenergy of reflected Be: < 10 eVenergy of reflected D: < 15-40 eV- low fluxes:Be flux: <3·1014 cm-2s-1
D flux: <3·1015 cm-2s-1
- radial inhomogeneity
DC reflex-arc discharge within airtight Be enclosure
high flux codeposit
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
H.W. Xu et al., Fusion Sci. Technol. 51, 547-552 (2007)
model system: magnetron sputtered Be
3 x 100Watt,6 mTorr,80% Ar, 20% D2
energy of sputtered Be: few eVenergy of reflected Ar: few eVenergy of ionized Ar: <120 eVenergy of D ions: <120eV
Be flux: 2.5·1015 cm-2s-1
+ up to 30 identical samples at a time
2 mm W spheres
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
D release from multilayer codeposits
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
D release from multilayer codeposits
Present predictions for T release in ITER are based on pure Be targets /
codeposits.
Actual ITER codeposits will be multilayers with BeO interfaces in between.
Be/D
Be/D
BeO
Question: Do BeO layers influence the D
release?
here: - collecting PISCES-B on W witness
- interrupted exposure for several hours / bring to air to allow an oxide layer
to grow
Diffusion barrier? Shift in release temperature?
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
experiment: low flux codeposit
- single layer: Be target + cap, bias = -100V ED = 22 eV = 1.2 · 1014 Be/cm-2s-1, t = 10000 sec
D release from single layer codeposit
W
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
100 200 300 400 500 600
1E-3
0.01
0.1
1
D fl
ux (1
016 D
/s)
sample temperature (°C)
PISCES-B, 300 K single layer
0.3 K/sec
2.41017D/cm2
tms2
2CW
B
experiment: low flux codeposit
- single layer: Be target + cap, bias = -100V ED = 22 eV = 1.2 · 1014 Be/cm-2s-1, t = 10000 sec
D release from single layer codeposit
TDS:
d = 100 nmD/Be = 0.2
W
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
100 200 300 400 500 600
1E-3
0.01
0.1
1
8.91017D/cm2
4.81017D/cm2
D fl
ux (1
016 D
/s)
sample temperature (°C)
PISCES-B, 300 K first layer second layer
0.3 K/sec
4.21017D/cm2
tms2
1CW
B / t
ms2
2CW
B
experiment
- 2 identical runs: Be target + cap, bias = -100V ED = 22 eV = 1.2 · 1014 Be/cm-2s-1, t = 10000 sec
- replacing one half piece of circular W witness plate after first run
D release from multilayer codeposit
TDS:
d = 2 x 100 nmD/Be = 0.2
BeOexpected 5-10 nm
W
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
100 200 300 400 500 600
1E-3
0.01
0.1
1
8.91017D/cm2
4.81017D/cm2
D fl
ux (1
016 D
/s)
sample temperature (°C)
PISCES-B, 300 K first layer second layer double layer
0.3 K/sec
4.21017D/cm2
tms2
1CW
A / t
ms2
1CW
B / t
ms2
2CW
B
experiment
- 2 identical runs: Be target + cap, bias = -100V ED = 22 eV = 1.2 · 1014 Be/cm-2s-1, t = 10000 sec
- replacing one half piece of circular W witness plate after first run
D release from multilayer codeposit
TDS:
d = 2 x 100 nmD/Be = 0.2
BeOexpected 5-10 nm
W
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
conclusion:
oxide interfaces (several nm thick) do not influence D release
D release from multilayer codeposit
100 200 300 400 500 600
1E-3
0.01
0.1
1
8.91017D/cm2
4.81017D/cm2
D fl
ux (1
016 D
/s)
sample temperature (°C)
PISCES-B, 300 K first layer second layer double layer sum first+second
0.3 K/sec
4.21017D/cm2
tms2
1CW
A / t
ms2
1CW
B / t
ms2
2CW
B
d = 2 x 100 nmD/Be = 0.2
BeOexpected 5-10 nm
W
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
comparing different codeposits
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
PISCES-B low flux (witness plate) codeposit
collecting Be and D (on W) sputtered/reflected from a Be target:
thermal desorption:
100 200 300 400 500 600
1E-4
1E-3
0.01
0.1
1
D fl
ux (1
016 D
cm
-2s-1
)
sample temperature (°C)
sum as D2
as HD
tms2
1CW
B
structurally modified, supersaturated(D2 bubbles / a-Be-D)
Be-D2 BeO defects bycoll. cascade
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
100 200 300 400 500 600
0.01
0.1
1
nD = 4.2 1017 D/cm2
low flux codeposit:D = 2.4 1015 D/(cm2s)
Be = 1.2 1014 Be/(cm2s)EBe< eV, ED= 21 eVT = 320 Kt = 10000 secD/Be = 0.34, d= 100 nm
rem
aini
ng D
(DT/D
0)
sample temperature T (°C)
tms-
22-C
-W-B240°C: 16%
350°C: 4%
PISCES-B low flux (witness plate) codeposit
collecting Be and D (on W) sputtered/reflected from a Be target:
thermal desorption:
100 200 300 400 500 600
1E-4
1E-3
0.01
0.1
1
D fl
ux (1
016 D
cm
-2s-1
)
sample temperature (°C)
sum as D2
as HD
tms2
1CW
B
ρ = 1.8 ·1017 D cm-2 / µmor: D/Be = 1.5%
structurally modified, supersaturated(D2 bubbles / a-Be-D)
Be-D2 BeO
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
thermal desorption:
high flux codeposit: collecting Be and D at floating target in Be seeded D discharge
PISCES-B high flux (target) codeposit
100 200 300 400 500 600
1E-4
1E-3
0.01
0.1
1 0.1 K/sec
D fl
ux (1
016 D
cm
-2s-1
)
sample temperature (°C)
sum as D2
as HD
BeL
SR
17gr
owth
100 200 300 400 500 600
0.01
0.1
1
nD = 1.54 1018 D/cm2
high flux codeposit:D = 3 1018 D/(cm2s)
Be = 1 1016 Be/(cm2s)ED=15 eVT = 320 Kt = 1000 secD/Be = 0.15, d = 825nm
rem
aini
ng D
(DT/D
0)
sample temperature T (°C)
BeLS
R17
grow
th
240°C: 4%350°C: 2%
ρ = 5 ·1016 D cm-2 / µmor: D/Be = 0.5 %
structurally modified, supersaturated(D2 bubbles / a-Be-D)
Be-D2 BeO defects bycoll. cascade
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
100 200 300 400 500 600
0.01
0.1
1
nD = 1.3 1017 D/cm2 seeded target erosion:jD = 2.5 1018D/(cm2s)
jBe = 2.2 1016 Be/(cm2s)
= - 2.1 1016 Be/(cm2s)
ED=150 eVT = 320 Kt = 10400 secD/Be = ?, d < 8 nm
rem
aini
ng D
(DT/D
0)
sample temperature T (°C)
BeLS
R12
240°C: 12%350°C: 6%
PISCES-B target
thermal desorption:
retention during net erosion:
ρ = 1.5 ·1017 D cm-2 / µmor: D/Be = 1%
100 200 300 400 500 6001E-5
1E-4
1E-3
0.01
0.1
1 0.3 K/sec
D fl
ux (1
016 D
cm
-2s-1
)
sample temperature (°C)
sum as D2
as HD
BeLS
R12
structurally modified, supersaturated(D2 bubbles / a-Be-D)
Be-D2 BeO defects bycoll. cascade
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
100 200 300 400 500 600
0.01
0.1
1
magnetron codeposit:D = ?
Be = 1.4 1015 Be/(cm2s)ED=120eVT = 320 Kt = 9000 sec=>3 at.% D, d= 1 m
rem
aini
ng D
(DT/D
0)
sample temperature T (°C)
W-G
A70
240°C: 82%350°C: 36%
nD = 4.0 1017 D/cm2
magnetron sputtered films
thermal desorption:
collecting Be/D sputtered from a Be target in Ar/D2 :
ρ = 1.4 ·1017 D cm-2 / µmor: D/Be = 0.8%
100 200 300 400 500 600
0.01
0.1
1
D fl
ux (1
016 D
cm
-2s-1
)
sample temperature (°C)
sum as D2
as HD
W-G
A70
structurally modified, supersaturated(D2 bubbles / a-Be-D)
Be-D2 BeO defects bycoll. cascade
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
the total amount of D retained above 350°C is the similar for all codeposits investigated:
ρ ≈·1017 D cm-2 / µm
(D/Be ≈ 1%)
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
D release from thick codepositsduring long holds @ 240°C (510K) and 350°C (620K)
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
D release from magnetron sputtered D/Be @ 240°C
0 2000 4000
0.01
0.1
1
100
200
300
400
500
600
700D
flux
(1015
D c
m-2s-1
)
time (sec)
reference run no hold 1 h hold 5 h hold 24 h hold
0.3
K/se
c
ramp tem
perature (°C)
1st ramp + hold
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
D release from magnetron sputtered D/Be @ 240°C
0 2000 4000
0.01
0.1
1
100
200
300
400
500
600
700
D fl
ux (1
015 D
cm
-2s-1
)time (sec)
reference run no hold 1 h hold 5 h hold 24 h hold
0.3
K/se
c
ramp tem
perature (°C)
2nd ramp
0 2000 4000
0.01
0.1
1
100
200
300
400
500
600
700
D fl
ux (1
015 D
cm
-2s-1
)
time (sec)
reference run no hold 1 h hold 5 h hold 24 h hold
0.3
K/se
c
ramp tem
perature (°C)
1st ramp + hold
time constant of hours!
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
D release from magnetron sputtered D/Be @ 240°C
0 5 10 15 20 250
20
40
60
80
100
log(hold time)
rele
ased
D fr
actio
ns (%
)
hold time (h)
sum
1st ramp to 240°C/510 K
hold at 240°C / 510 K
2nd ramp to 650°C / 920 K
1.0 ·1017 D cm-2 remainsafter hold
or: D/Be = 0.8%
extrapolating to 690 m2 ITER main wall: 9 g D per µm remains after 24h @ 240°C
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
D release from magnetron sputtered D/Be @ 350°C
0 2000 4000
0.01
0.1
1
100
200
300
400
500
600
700
D fl
ux (1
015 D
cm
-2s-1
)time (sec)
reference run no hold 1 h hold 5 h hold 24 h hold
0.3
K/se
c
ramp tem
perature (°C)
C:\Dokumente und Einstellungen\tms\Eigene Dateien\Projekte\PISCES\Daten\GA coater\ W-GA70s-holds-ramps.opj(350fluxtest2) 04.05.201
2nd ramp
0 2000 4000
0.01
0.1
1
100
200
300
400
500
600
700
D fl
ux (1
015 D
cm
-2s-1
)
time (sec)
reference run no hold 1 h hold 5 h hold 24 h hold
0.3
K/se
c
ramp tem
perature (°C)
C:\Dokumente und Einstellungen\tms\Eigene Dateien\Projekte\PISCES\Daten\GA coater\ W-GA70s-holds-ramps.opj(350fluxtest) 04.05.2011 17:01:14
1st ramp + hold
time constant of hours!
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
D release from magnetron sputtered D/Be @ 350°C
0 5 10 15 20 250
102030405060708090
100110
2nd ramp to 650°C/920 K
sum
1st ramp to 350°C/620 K
hold at 350°C/620 K
rele
ased
D fr
actio
ns (%
)
hold time (h)
2.5 ·1016 D cm-2 remainsafter hold
or: D/Be = 0.2%
extrapolating to 690 m2 ITER main wall: 2.5 g D per µm remains after 24h @ 350°C
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
modeling D release with diffusion and trapping
implemented mechanisms:
- diffusion of D through BeD with
- trapping and de-trapping of D at 2 binding sites (one with, one without re-trapping)
CRDS-code (“coupled reaction diffusion system” by Matthias Reinelt*) = flexible code for simulation of such systems
Simple model: diffusion coupled with de-trapping (and re-trapping) from binding sites
D2
D
ED, nD
ET2, nT2
ET1, nT1
D0 e-ED/kBT
e-ET/kBT
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
modeling D release with diffusion and trapping
CRDS-code (“coupled reaction diffusion system” by Matthias Reinelt*) = flexible code for simulation of such systems
Simple model: diffusion coupled with de-trapping (and re-trapping) from binding sites
0 1000 2000 3000
0.01
0.1
1
D fl
ux (1
015 D
cm
-2s-1
)
time (sec)
experiment model temperature
0.3 K
/sec
nD = 4 1017 D/cm2
0.01
0.1
1
100
200
300
400
500
600
700
tem
pera
ture
(°C
)
implemented mechanisms:
- diffusion of D through BeD with
- trapping and de-trapping of D at 2 binding sites (one with, one without re-trapping)
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
discussion of the fit:
- although ramp better described
- hold @ 240°C: model incorrectly predicts too much desorption during the hold
modeling D release with diffusion and trapping
0 2000 4000 6000 8000
0.01
0.1
1
240°C
D fl
ux (1
015 D
cm
-2s-1
)
time (sec)
650°C
experiment model temperature
240°C hold
0.01
0.1
1
100
200
300
400
500
600
700
800
tem
pera
ture
(°C
)
analysis of independent measurements simultaneously
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
modeling D release with diffusion and trapping
- ramp and hold desorption behaviorfairly well reproduced
- model shows sharper desorptionpeaks than observed in experiment
- outgassing above 450°C to fast insimulation
0 2000 4000 6000 8000
0.01
0.1
1
D fl
ux (1
015 D
cm
-2s-1
)
time (sec)
240°C hold
0.01
0.1
1
experiment model temperature
100
200
300
400
500
600
700
800
tem
pera
ture
(°C
)
present status:
Next step: implementing decomposition
tool to interpolate
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
summary
magnetron sputtered Be/D films are suited as a model system to study retention and release
release of D from Be at 240°C and 350°C has a very large time constant
even a several hours bake at 240°C or 350°C does not release all D(a D/Be of 0.8% or 0.2% remains, respectively)(deeper trap sites that cannot be drained)
codeposits grown in different ways (energies, growth rates) show similar release features
the total amount of D released above 350°C is the same for all codeposits investigated, equivalent to D/Be ≈ 1%
multilayer codeposits show the same release as single layer codeposits (BeO interface is no transport barrier)
D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011
U C S DUniversity of California San Diego
Thanks to:
PISCES team:
Russ DoernerMatt BaldwinDaisuke NishijimaTimo DittmarJonathan YuTyler LynchKarl UmstadterRay SeraydarianLeo ChousalRolando Hernandez