Effects of repeated short heat pulses on tungsten

Effects of ELM-like repeated short heat pulses on tungsten have been studied by using a fundamental wave (wave length of 1064 nm, the pulse length of 130 μs) of a Nd/YAG laser. Tungsten temperature was 773 K or 473 K. The energy absorption rate of the laser light was about 30% for mirror-finished surface. After 10,000 shots at an incident energy fluence of 7 J/cm2 (melting threshold was about 150 J/cm2), the cracks formation was still observed. Surface roughening and cracking were more pronounced for tungsten samples with surface impurity mixing layers (carbon and oxygen).