1. Institute for Plasma Physics Rijnhuizen D retention in W and mixed systems in Pilot-PSI G. De Temmerman a, K. Bystrov a, L. Marot b, M. Mayer c, J.J. Zielinski a, R. tHoen a, G. Wright a,d, and J. Rapp a a FOM Institute for Plasma Physics Rijnhuizen, Ass. EURATOM FOM, Nieuwegein, NL b Department of Physik, University of Basel, Basel, Switzerland c Max-Planck Institut fuer Plasmaphysik, EURATOM Association, Germany d PSI Science Centre, PSFC, MIT, Boston, USA

2. G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010 Pilot-PSI. Experimental set-up TS T e (r) n e (r) Pilot-PSI is a linear plasma device producing ITER-divertor like plasmas Magnetic field up to 1.6T Plasma conditions: 0.1-10x10 20 m -3, 0.1-5eV

3. 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

4. G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010 TRIM simulation with E d = 40 eV T target = 300 K Irradiation by energetic W 4+ 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

5. G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010 Depth profiles, High T surf, 0 mm T surf = 920 K Concentrations are low, but enhanced in the damaged are ( 2 um.

6. G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010 Depth profiles, Low T surf, 0 mm Damaged zone still enhanced (fully?) to roughly equivalent or slightly less than surface zone. D still clearly diffusing into damaged zone. T surf = 480 K

7. 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.

8. G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010 Future work Irradiation energy determines depth of damage Variation of the damage profile and effect on D retention TRIM calculations

9. 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). Future work

10. 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 dpa 1 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

11. 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

12. 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

13. G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010 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

14. 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

15. 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

16. G. De Temmerman Meeting of the SEWG on high-Z materials, Garching, July 2010 Transient heat/particle pulses in Pilot-PSI 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)

17. 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 (140x10 22 m -3, 6eV) corresponding to peak heat flux of 1GW.m -2

18. 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

19. 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)