Thermal shock behaviour of H and H/He-exposed tungsten at high temperature

Abstract

Abstract. Polycrystalline tungsten samples were characterized and exposed to a pure H beam or mixed H/He beam containing 6% He in GLADIS at a surface temperature of 600°C, 1000°C, or 1500°C. After 5400 s of exposure time with a heat flux of 10.5 MW/m 2 , the total accumulated fluence of 2×10 25 m −2 was reached. Thereafter, ELM-like thermal shocks with a duration of 1 ms and an absorbed power density of 190 MW/m 2 and 380 MW/m 2 were applied on the samples in JUDITH 1. During the thermal shocks, the base temperature was kept at 1000°C. The ELM-experiments with the lowest transient power density did not result in any detected damage. The other tests showed the beginning of crack formation for every sample, except the sample preexposed with the pure H-beam at 1500°C in GLADIS. This sample was roughened, but did not show any crack initiation. With exception to the roughened sample, the category of ELM-induced damage for the pre-exposed samples is identical to the reference tests without pre-exposure to a particle flux.