Performance of deformed tungsten under ELM-like plasma exposures in QSPA Kh-50

Cracking thresholds and crack patterns (major- and micro-) as well as residual stresses in tungsten targets after repetitive ITER ELM-like plasma pulses have been studied in recent simulation experiments in the quasi-stationary plasma accelerator QSPA Kh-50. Experiments were carried out for preheated samples of ITER reference grade of tungsten (with elongated grains). The QSPA plasma exposures were performed for the targets preheated at 200 deg. C, 400 deg. C and 600 deg. C, to estimate effects of Ductile-to-Brittle Transition Temperature (DBTT) on cracking development. Tungsten surface was analyzed after 1 pulse, 5 pulses and 10 pulses of 0.25 ms time duration to investigate the influence of material modification by plasma exposures on cracking thresholds. The magnitude of heat load was 0.2 MJ/m2, 0.3 MJ/m2, 0.45 MJ/m2 (without melting) and 0.75 MJ/m2 (above the melting threshold).