Review of Works on Plasma-Surface Interaction at the Budker Institute

Since the 1990s, comprehensive studies of the interaction of powerful plasma streams, electron beams, and laser radiation with solid bodies have been carried out at the Budker Institute of Nuclear Physics under loads expected at the first wall of a fusion reactor. First, the experiments have been performed using the GOL-3 facility, then the BETA bench. At the moment, new experimental facilities are being set up, including the Plasma Station at the under-construction SKIF synchrotron radiation source, and a new-generation open-trap GDMT reactor is being designed. The properties of near-surface plasma and its dynamics (density, temperature, velocity, charge composition) have been investigated using the developed diagnostic complex of the GOL-3 multimirror trap. Surface modification of various materials (tungsten, graphite, ceramics) under different pulse thermal loads has been studied. The use of the electron beam on BETA bench allowed in situ observation of surface modification processes during thermal shock, which is unavailable for plasma impact facilities. Comparison with the data of other researchers has been performed and their consistency with each other has been shown. Thresholds for cracking and melting of tungsten, explosive (brittle) fracture of graphite have been obtained. Synchrotron radiation has been used to study stresses in materials, with which stresses during pulsed irradiation have been measured with high temporal resolution. Experimental work is supplemented by theoretical and computational studies. A model of tungsten fracture is proposed according to which stresses leading to tungsten cracking occur at the cooling stage. For the first time in the world, the appearance of cracks significantly later than the thermal load has been experimentally observed using the BETA bench.