H/He irradiation on tungsten exposed to ELM-like thermal shocks

ELM-like thermal shocks and H/He particle exposure were subsequently applied on tungsten samples. Polished test specimens underwent in the JUDITH 1 electron beam facility 100 transient thermal events with a duration of 1 ms. The absorbed heat flux was 0.4 GW m(-2) and 1.5 GW m(-2), which is above the material's damage threshold. These experiments were done at room temperature and with the samples heated to 400 degrees C base temperature. Depending on the loading conditions the test specimens have either a crack network or showed surface roughening. The samples were then loaded in the GLADIS facility at different surface temperatures with a mixed H/He beam with a flux of 3.7 x 10(21) m(-2) s(-1). Post-mortem analysis showed that the roughened surface did not alter the H/He induced surface modifications. In contrast to that on the test specimens that exhibited crack formation, phenomena such as bubble creation along the crack edge, formation of a shallow layer of nano-structures covering the crack opening, and the emerging of a porous structure which partially fills the crack are observed. (C) 2016 EURATOM. Published by Elsevier B.V. All rights reserved.