Comparative analysis of damageability produced by powerful pulsed ion/plasma streams and laser radiation on the plasma-facing W samples

Abstract

Parallel use of directed plasma/fast ion streams from Dense Plasma Focus and of laser radiation (in a free running and Q-switched modes) for irradiations of targets looks perspective for tests of materials designed to withstand extreme thermal loads in the mainstream fusion reactors with inertial and magnetic plasma confinement. It is so because of a wide range of power flux densities and pulse durations generated by them. Tungsten is counted as the most appropriate material for the plasma-facing components. Main features of degradation of the surface layer of double forged tungsten were determined at different conditions of its irradiation by these streams. Chief similarities and differences in damageability obtained in the regimes are fixed – blisters, craters, porosity, microcracks, and discontinuity flaws etc. – that are peculiar characteristics for each mode of irradiation. The observed resemblances and dissimilarities that are specific for each regime of irradiation are explained with the help of numerical modelling of the treatment processes. It is shown that a so-called Integral Damage Factor may be used only in restricted ranges of parameters of an irradiation. It was found that in the regime of irradiation with the well-developed gas dynamic motion of secondary plasma the overall energy of radiation will be spent preferentially either on mass removal from the material's surface or on heating of a small amount of matter to high temperature (and consequently into its fast movement) depending on power flux density of radiation and its pulse structure.