Experimental and Numerical Study of Damage Caused by High-Current Electron Beam to Construction Materials Intended for the First Wall of Powerful Plasma Installations

Abstract

An experimental study of the effect of high-current electron beams on crystals made of polycrystalline tungsten and corrosion-resistant ferritic-martensitic steel EK-181 was carried out, as well as a numerical simulation of the process of interaction of the beam with the target, in which the energy of the electron beam was absorbed in the near-surface layers of the samples under study. The experiments were carried out on the Kalmar high-current electron accelerator at an average pulse energy of E ≈ 100 ± 20 J (pulse duration at half maximum 100 ns). During the experiments, samples were irradiated from one to ten times. Numerical modeling was performed using electron spectra calculated on the basis of data (currents and voltages in the diode gap) obtained as a result of electrical measurements. The difference in the nature of destruction of tungsten and steel was demonstrated. It has been shown that tungsten begins to crack after three-pulse exposure with an energy of about 100 J, which correlates well with tests on other types of installations. On steel, minor cracking was observed only after 8–10 pulses of exposure. Numerous traces of droplets of melting and redeposition of the target material were found on the surface of the steel target. For both materials, the specific amount of energy absorbed in the region of interaction of the electron beam with the target was estimated.