institute of plasma physics and laser microfusion warsaw, poland status and prospect of mj plasma...
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Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Status and Prospect of MJ Plasma Focus Experiment
by
Marek Scholz
Institute of Plasma Physics and Laser Microfusion
Warsaw, Poland
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Outline1. Introduction
– Goals of experiment
2. Time evolution of PF discharge for two kinds of electrodes correlated with neutron emission
– Visualization of the pinch dynamics and structure
3. Neutrons measurements
4. Summary - upgrade of PF-1000
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Motivation
We can get easily high temperature plasma.
Unexpected high neutron yield is obtained.
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Neutron yield Yn
254
TI
a
lPlYn
v
v4
DDnNP
Tc
IND 2
2
4
v
a 2a
Nn D
D
for keVT 9 47106,1 Ia
lYn
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Scaling
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Large PF device
PF – 3 (Moscov), Eb = 3 MJ, Ub= 20 kV;
Frascati (Program Euroatom), Eb = 1 MJ; Ub= 50 kV;
Poseidon (Stutgart), Eb = 750 kJ; Ub= 80 kV;
PF-1000 (Warsaw), Eb = 1 MJ; Ub= 40 kV
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Scaling
EILL 202
1
0LL
EI 22EYn
Frascati (Program Euroatom), Eb = 1MJ; Ub= 50 kV;
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Main QuestionsThis observed saturation in the Yn is caused by the incorrect formation of a proper plasma sheath due to many reasons (e.g. impurities, sheath instabilities)
orThere exists a fundamental threshold for saturation in the Yn
Mechanism of neutron production in large PF facilities
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Poseidon (Stuttgart)
Typical neutron signal on Poseidon
• the compression phase (t<0)
• the quiescent phase (plasma expands to r 2rmin
• the instability phase (m=0)
• break-up of the plasma column caused by instability
Beam-Target !?
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Anisotropy
;124
30
20
u
EQE d
n
v
190
00
0
Y
YA
ED(keV) 20 100 300
En(00) (MeV)
2.56 2.80 3.06
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Goals of Experiment
Definition of the neutron emission characteristics (neutron anisotropy and spectra) from large PF facility;
Definition of the relation between the Yn and plasma sheath dynamics, with particular attention paid to structures appearing within the pinch column;
Definition of correlation between the neutron generation and other types of ionizing radiation produced within PF discharges, i.e. fast electrons, protons from DD reaction, soft and hard X-rays, etc
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Apparatus
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Generator PF-1000
the charging voltage - U0 = 20 - 40 kV,
the bank capacitance - C0 = 1.332 mF,
the bank energy - E0 = 266 - 1064 kJ,
the nominal inductance - L0 = 15 nH,
the quarter discharge time - T1/4 = 6 s,
the short-circuit current – ISC = 12 MA,
the characteristic resistance - R0 = 2.6 m,
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
ElectrodesCE diameter - 226 mm
OE diameter - 400 mm
OE consists 24 rods (diam. 32 mm)
length of electrode - 560 mm
length of insulator - 113 mm
CE diameter - 226 mm
OE diameter - 400 mm
OE consists 12 rods (diam. 80 mm)
length of electrode - 560 mm
length of insulator - 113 mm
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Diagnostics
v2
DDnNP
254
TI
a
lPlYn
v
Silver Activation Counter
(anizotropy)
PMT
TOF (spectra T)
Rogovski coilFrame cameras;
Streak camera
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Measurements of Current and Voltage
I(t)I(t)
dI/dtdI/dt
U(t)U(t)
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8
0,0
0,2
0,4
0,6
0,8
1,0
1,2
1,4
1,6
1,8
2,0
2,2
I [M
A]
time [s]
i_rog i_rog i_rog i_rog
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8-1,6-1,4-1,2-1,0-0,8-0,6-0,4-0,20,00,20,40,60,81,01,21,41,61,82,0
dI/d
t
time [s]
di1/dt di1/dt di1/dt di1/dt
-7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5-5
0
5
10
15
20
25
30
35
U [k
V]
time [s]
u_col u_col u_col
Ub= 27 kV, Eb= 480 kJ,
p = 3,5 Torr
Y = 51010 - 31011
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Compression, Pinch & Post-pinch
-170 ns -120 ns 0 ns 50ns 140 ns
Visible frames - exposure time 1 ns, window 589 nm
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Compression, Pinch & Post-pinch
XUV frames - exposure time 2 ns, window 200-300 eV+above 600 eV
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
1.0 1.5 2.0 2.5
HardXrays
SoftXrays
PINdiode
Electrons
dIdt
Neu180deg
time [s]
shot 3108
p = 3.00 TorrUb = 33.0 kV
Eb = 734.0 kJ
Imax = 1.66 MA
L1 = 77897
L2 = 66392
L3 = 47298
L4 = 78015
L5 = 31732
1.269 s 1.289 s 1.299 s
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Density at 10.2 s
-50.0 -40.0 -30.0 -20.0 -10.0 0.0 10.0 20.0 30.0-30.0
-20.0
-10.0
0.0
10.0
20.0
30.0
1E+019 cm^-3
2E+019 cm^-3
3E+019 cm^-3
4E+019 cm^-3
5E+019 cm^-3
6E+019 cm^-3
7E+019 cm^-3
8E+019 cm^-3
9E+019 cm^-3
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Visible streak-camera
4 cm
ns100 2000
implosion of the current sheath
first pinch developmentof instabilities
second pinchexplosion
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Visible frames - exposure time 1 ns, window 589 nm
a-d implosion 2x105m/se minimum radius t=0c-g intense light - dense plasma, dense spherical structureg-p instabilitiesj-m second pinch m-n second explosion m-p second dense structure
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
XUV frames - exposure time 2 ns, window 200-300 eV+above 600 eV
a-c pinch ø 1-2 cm;d – first expansione-f - second pinchg-i explosion, dense structuredense spherical structure
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Correlation of neutron signals with frames (first neutron pulse)
0
0,5
1
1,5
2
-100 0 100 200 300 400
[ns]
-50 ns 50 ns-30 ns -10 ns 0 ns 10 ns 30 ns
-10 ns-20 ns 30 ns -30 ns 0 ns
hard x-rays
neutron signal
onset of neutron pulse – zipper effect, beam-target decrease of neutrons – dense structure isotropic distribution
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
t1
t2
t2-t1=10ns
XUV frames - exposure time 2 ns, window 200-300 eV+above 600 eV
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
XUV frames - exposure time 2 ns, window 200-300 eV+above 600 eV
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Calculated density st 72,5
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Calculated temperature of ions
st 72,5
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
PM-355 detector
Aluminium foil
Small ion pinhole cameras equipped with PM-355 detectors were used to determine fusion-reaction proton emission sources.
To eliminate fast primary deuterons the detector samples used in the cameras were covered with 80 μm thick Al-foils..
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Positioning of ion-pinhole cameras within the PF-1000 facility during measurements of fusion-produced protons.
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Images of fusion-proton emitting areas, as obtained after etching of the PM-355 detectors irradiated during five successive discharges within the PF-1000 facility (operated at p0 = 4 Torr D2,
U0 = 31 kV).
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Example of the image of the fusion-produced protons, as recorded upon the detector placed at 900 to the z-axis in the PF-1000 facility.
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
S2 S1 S0 S4 S5 S8
SC1
SC3 SC2
Activation silver counters: SC1(30o), SC2(60o), SC3(90o), SC5(150o)
Scintillator PMT detectors: S0(58.34m, 0o), S1(16.33m, 0o),
S2(7m, 0o), S4(7m, 180o), S5(17m, 180o), S8(58.34m, 180o)
2.27m
Collector
Copper electrode
7 m
16.33m
58.34 m
SC5
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
SHOT 6543
1,8x10-6 2,0x10-6 2,2x10-6 2,4x10-6 2,6x10-6 2,8x10-6 3,0x10-6
-3
-2
-1
0
volta
ge
time [s]
7m, 90o
7m, 0o
7m, 180o
1,0x10-6 2,0x10-6 3,0x10-6 4,0x10-6 5,0x10-6 6,0x10-6
-0,06
-0,03
0,00
0,03
volta
ge
time [s]
58m, 0o
58m, 180o
1,0x10-6 2,0x10-6 3,0x10-6 4,0x10-6 5,0x10-6 6,0x10-6
-0,18
-0,09
0,00
volta
ge
time [s]
84m, 0o
84m, 180o
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
0 1 2 3 4 5 6 7 8-8
-7
-6
-5
-4
-3
-2
-1
0
1
volta
ge
[V]
time [s]
S0 S8
2 3 4 5 6-8
-4
0
2,88 MeV
t = 4,76-(2,26 - 0,195) sVol
tage
[V]
time [s]
S0t = 4,62-(2,33 - 0,195) s
2,45 MeV
2 3 4 5
-8
-4
0
2,14 MeV
t = 5,02 - (2,33 - 0,195) s
volta
ge [V
]
time [s]
S8
SHOT 5566
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Results of TOF measurements
Shot
number
Yn
L1(90o)
tn (0O)
[s]
tn (180O)
[s]
t=tn (180O) - tn (0O)
[s]
Eb [keV]
5544 2.03.1011 4.734 5.055 0.321 70.0
5566 1.49.1011 4.615 5.035 0.420 120
5569 1.76.1011 4.643 4.965 0.322 70.4
5575 1.92.1011 4.509 4.789 0.280 53.2
5592 1.34.1011 4.623 4.911 0.288 56.3
5605 2.28.1011 4.770 5.158 0.388 102
5620 1.14.1011 4.860 5.147 0.287 55.9
5649 1.55.1011 4.573 4.874 0.301 61.5
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
PF-1000, 1,8 MA,
Y 31011 n/shot,
E=480 kJ
A “historical” experimental scaling law for neutron yield as a function of the total dischargecurrent (assembled in 1975).
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Measurements of Current and Voltage
I(t)I(t)
dI/dtdI/dt
U(t)U(t)
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8
0,0
0,2
0,4
0,6
0,8
1,0
1,2
1,4
1,6
1,8
2,0
2,2
I [M
A]
time [s]
i_rog i_rog i_rog i_rog
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8-1,6-1,4-1,2-1,0-0,8-0,6-0,4-0,20,00,20,40,60,81,01,21,41,61,82,0
dI/d
t
time [s]
di1/dt di1/dt di1/dt di1/dt
-7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5-5
0
5
10
15
20
25
30
35
U [k
V]
time [s]
u_col u_col u_col
Ub= 27 kV, Eb= 480 kJ,
p = 3,5 Torr
Y = 51010 - 31011
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
-8,0x10-6-6,0x10-6-4,0x10-6-2,0x10-6 0,0 2,0x10-64,0x10-66,0x10-68,0x10-61,0x10-5
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
1
Y A
xis
Titl
e
time [s]
4,0x10-7 6,0x10-7 8,0x10-7 1,0x10-6 1,2x10-6 1,4x10-6 1,6x10-6 1,8x10-6 2,0x10-6
-1,0
-0,5
0,0
Y A
xis
Titl
e
time [s]
8m, 0o
8m, 90o
8m, 180o
SHOT 6543
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
PF-1000, 1,8 MA,
Y 31011 n/shot,
E=480 kJ
A “historical” experimental scaling law for neutron yield as a function of the total dischargecurrent (assembled in 1975).
PF-1000, 1,95 MA,
Y 61011 n/shot,
E=550 kJ
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Question for future
Determination of parameters of the dense plasma structure in the head of the pinch
role of outflow role of disipation procesess of magnetic
field energy into a pinch plasma naturenature of neutron generation of neutron generation
Correct neutron measurements
Measurements of a current flowing in a pinch
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Diagnostics
v4
DDnNP
254
TI
a
lPlYn
v
Activation Measurements
(anizotropy !!)
Method of calibration!
PMT
TOF (spectra Ti)
Current probesInterferometry !!;
Streak cameraSoft X-ray Measurements
(D+Ar or D+Kr)
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Interferometry for PF-1000
Laser output specyfication
Max. Pulse energy, mJ
At 1053 nm 1000
At 527 nm 450
At 351 nm 320
At 263 nm 160
Pulse duration at 1053 nm (FWHM) < 1 ns
Optical pulse jitter +/-1 ns
Beam divergence at 1053 nm (ful angle @ 1/e2) < 0.25 mrad
Beam diametr 12 mm
Mach-Zenhder
16 frames, 60 ns between frames
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
5 00 1 0 0 1 5 0 2 0 0 2 5 0 3 0 0
Sonda scyntylacyjna prod. ACS
Obudowa licznika scyntylacyjnego-wersja 08
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Cut view of MCNP geometry of PF-1000 facility.
Cathode
AnodeNeutron source(Pinch)
Concrete hall structure
Chamber
X
IV
J I
V II
III
Detector Z
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
RSF ( Response Scaling Factor) as a function of detector angular position.
RSF =Response( 2.5 MeV source) / Response( Am-Be source).
1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2
RSF
0 31 50 90 150
Detector angular position [deg]
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Thermal neutron flux as a function of detector position calculated for point 2.5 MeV neutron source located on ‘Z’ axis and distanced 0.1,
0.2, 0.5, 2, 4, 6 and 8 cm from the anode
5.00E-07
1.00E-06
1.50E-06
2.00E-06
2.50E-06
0 20 40 60 80 100 120 140
Detector angular position [deg]
Neu
tro
n f
lux
[n/c
m2]
0.01cm 2cm4cm 6cm
8cm 0.02cm0.05cm
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Idea of the method
Fast neutron interactions
(n,n’) tch 10-12 s
(n,), (n,n’), (n,2n)
(n,p), (n,), (n,)T1/2 s
n
r
A
MNY A
aA
MNF A
TA eaA
MNA 10
dEEE
Institute of Plasma Physics and Laser MicrofusionWarsaw, Poland
Procedure of calibration
n
r
s
n
K
EES ,
exp
exp
TA eANMa
A
1/0
Calibration source with defined S1.
2. MCNP modelling including:
defined calibration source;
all masses surrounding the source;all masses surrounding the source;
defined samplesdefined samples
s
n
K
EES
cal
cal ,
3. MCNP modelling including:
DD neutron source (plasma) Yn;
all masses surrounding the source;all masses surrounding the source;
defined samplesdefined samples
s
n
K
EEY
DD
DDn ,