institute for plasma physics rijnhuizen d retention in w and mixed systems in pilot-psi g. de...
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Institute for Plasma Physics Rijnhuizen
D retention in W and mixed D retention in W and mixed systems in Pilot-PSIsystems in Pilot-PSI
G. De Temmermana, K. Bystrova, L. Marotb, M. Mayerc, J.J. Zielinskia, R. t’Hoena, G. Wrighta,d, and J. Rappa
aFOM Institute for Plasma Physics Rijnhuizen, Ass. EURATOM FOM, Nieuwegein, NL
bDepartment of Physik, University of Basel, Basel, Switzerland
cMax-Planck Institut fuer Plasmaphysik, EURATOM Association, Germany
d PSI Science Centre, PSFC, MIT, Boston, USA
G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010
Pilot-PSI. Experimental set-up
TSTe (r)
ne (r)
Pyrometer
Source
Plasma jet
TargetB
Coils
Water cooling
To pumps
CH spectrometer
Thomsonscattering
Pilot-PSI is a linear plasma device producing ITER-divertor like plasmas
Magnetic field up to 1.6T
Plasma conditions: 0.1-10x1020m-3, 0.1-5eV
G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010
Outline
Deuterium retention in damaged tungsten
Deuterium retention in mixed W/C layers
Effect of transient heat loads on D retention
G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010
0
0.5
1
1.5
2
2.5
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
Depth (microns)
dis
pla
cem
ents
per
ato
m (
dp
a)
TRIM simulation with Ed = 40 eV
Ttarget = 300 K
Irradiation by energetic W4+ ions
Irradiation of tungsten by 12.3 MeV ions to simulate neutron damage and study its influence on D retention
Targets irradiated at IPP Garching with various dpa
Plasma exposure in Pilot-PSI (fluence, temperature)
1) G.M.Wright, M. Mayer, K. Ertl, G. de Saint-Aubin and J. Rapp, Nucl. Fusion 50 (2010) 075006
600
650
700
750
800
850
900
950
-8 -6 -4 -2 0 2 4 6 8
Radial position (mm)
Su
rfac
e T
emp
erat
ure
(K
)
G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010
Depth profiles, High Tsurf, 0 mm
Tsurf = 920 K
• Concentrations are low, but enhanced in the damaged are (<2 um) and approximately identical to 0 dpa case for >2 um.
G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010
Depth profiles, Low Tsurf, 0 mm
• Damaged zone still enhanced (fully?) to roughly equivalent or slightly less than surface zone. D still clearly diffusing into damaged zone.
Tsurf = 480 K
G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010
Retention vs Temperature
• Retention is peaked at moderate (~500 K) temperatures but this is also assuming no fluence dependence.
0
2
4
6
8
10
12
14
16
18
20
300 400 500 600 700 800 900 1000
Temperature (K)
D r
eta
ine
d in
fir
st
4 u
m (
10
20 D
/m2 )
2 dpa
0 dpa
G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010
Future work
Damage profile at different irradiation energies
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
depth (mu)
dp
a le
ve
l
5MeV Ed=40eV
10MeV Ed=40eV
12MeV Ed=40eV
15MeV Ed=40eV
21MeV Ed=40eV
Irradiation energy determines depth of damage
Variation of the damage profile and effect on D retention
TRIM calculations
G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010
A flat damage profile up to 1.5 μm depth can be obtained by a combination of ion-beam-irradiation with different ion energies (≤21MeV).
Flat damage profile
0
0.1
0.2
0.3
0.4
0.5
0.6
0 0.5 1 1.5 2
depth (mu)
dp
a-l
ev
el
5MeV Ed=40eV
10MeV Ed=40eV
12MeV Ed=40eV
15MeV Ed=40eV
21MeV Ed=40eV
sum
Future work
G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010
Experimental plan
Saturation of the D retention enhancement is measured at a level ≤ 0.5 dpa1
Investigate the threshold behavior
- peak damage levels of 0/0.1/0.2/0.5 dpa
Investigate the influence of different irradiation profiles
- peaked profile
- flat profile
1) Irradiation with ion-beam-accelerator at IPP Garching (9-11 August)
2) Plasma exposure at Pilot –PSI (12-13 August)
3) D retention analysis by NRA and TDS
G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010
Outline
Deuterium retention in damaged tungsten
Deuterium retention in mixed W/C layers
Effect of transient heat loads on D retention
G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010
D retention in mixed W/C systems
Preparation of W/C layers by magnetron sputtering on W substrates
Dual magnetron system
Independent variation of W and C deposition rate
In-situ XPS analyses
Ar/D working gas
Mixed W/C to be exposed to pure D and mixed D/He plasmas in Pilot-PSI
Effect of plasma exposure on film composition and retention
G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010
295 290 285 280 275 270
C 1s
Inte
nsi
tiy
[a.u
.]
Binding energy (eV)
42 40 38 36 34 32 30 28 26
W 4f
Inte
nsi
ty [
a.u
.]
Binding energy (eV)
Film composition
First tests done on Si substrates to study the film composition as a function of deposition parameters
Composition varied from pure W to pure C film
Ar as working gas
RT
Films consist of a mixture of W, C and WC
G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010
Plasma exposure in Pilot-PSI and TEXTOR
Samples being prepared for exposure in Pilot-PSI Effect of surface temperature on retention and film composition (mixing)
Effect of He addition on retention and mixing
Experiments planned for October 2010
Similar samples to be exposed in the SOL of TEXTOR Using similar layers ensure a better comparability
Experiment in divertor-like and SOL plasma
G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010
Outline
Deuterium retention in damaged tungsten
Deuterium retention in mixed W/C layers
Effect of transient heat loads on D retention
G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010
Transient heat/particle pulses in Pilot-PSI
NozzleCathode
Gas inlet PlatesTarget
++
W
W
W
B ≤ 1.6T Cooling system
Fast infrared camera (30kHz) for temperature measurements
IR
Plasma source
C
Laser beam =532nm for Thomson scattering
WC
17mm
8400μF
Power supply
Capacitor bank
+++
+++
+++
+++
+++
+++ +++
+++
+++
+++
+++
++
Plasma source modified to allow very high power operation
In parallel to DC power supply, discharge current transiently increased by discharging capacitor in source
Pulsed plasma superimposed on steady-sate plasma (different from QSPA)
In addition, pulsed bias system being developed (-100V reached)
G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010
Transient heat/particle pulses in Pilot-PSI
Plasma conditions depend on source geometry, gas flow, input power, B field
Temperature rise time of 300-500us, typical of tokamak ELMs
Record plasma conditions (140x1022m-3, 6eV) corresponding to peak heat flux of 1GW.m-2
1019 1020 1021 1022 10230.1
1
10
1026 m-2 s-11024 m-2 s-1
Ele
ctro
n t
emp
erat
ure
(eV
)
Electron density (m-3)
1025 m-2 s-1
G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010
MAGNUM ELM Simulation System
Current system to be upgraded for high repetition rate (budget agreed)
New system designed to allow 2 GW.m-2 , 0.5ms, 10Hz
Operations at higher repetition rates (up to 70Hz) possible at lower power
Transient target bias synchronized with pulsed plasma
Current system fully operational
Fast IR camera (SC 7500, FLIR) installed
Pulsed bias system commissioned
G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010
Transient heat/particle load on retention
First experiments in July 2010 Fixed steady-state plasma and varying transient heat load
Analysis ongoing (TDS)