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 °C, 400 °C and 600 °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).