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P: Fachverband Plasmaphysik

P 3: Plasma Wall Interactions

P 3.5: Talk

Monday, March 2, 2015, 15:40–15:55, HZO 50

Interaction of Deuterium Plasma with Sputter-deposited Tungsten Nitride Films — •Liang Gao^1,2, Wolfgang Jacob¹, Thomas Schwarz-Selinger¹, Armin Manhard¹, and Gerd Meisl¹ — ¹Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany — ²Ruhr-Universität, Bochum, Universitätsstraße 150, 44801 Bochum

N2 seeding is frequently used for radiative power dissipation in fusion devices with full-tungsten divertor, such as ASDEX-Upgrade and JET. N implantation into W or redeposition of W in the presence of N may produce N-containing W surfaces. Magnetron-sputtered tungsten nitride (WNx) films were exposed to deuterium (D) plasmas to mimic the interaction of D plasmas with such re-deposited layers. RBS and NRA were employed to measure the composition of WNx, , erosion by D plasma and D retention. D implantation was performed with ion energies below 215 eV at sample temperatures of 300 K and 600 K. Low energy Ar plasma exposure was combined with NRA measurements for D depth profiling in the uppermost nanometers. The experimental results are compared with SDTRIM.SP simulations. Results show that D was only retained within the ion penetration range for samples exposed at 300 K. At 600 K, the total amount of retained D decreases by 50% compared with 300 K and D diffuses beyond the implantation zone. Annealing of the WN prior to D implantation can partially heal the D trap-sites thus reducing the retained D in the implantation zone by about 10%.