A study of the radiation-thermal resistance of ferritic steel 16Cr – 4Al – 2W – 0.3Ti – 0.3Y2O3 was made. This ODS (oxide dispersion strengthened) steel is perspective for fusion applications. The “Vikhr” Plasma Focus installation was used to introduse of powerful pulsed flows of helium ions and helium plasma. The power density of a beam of fast helium ions and high-temperature helium plasma flows was ~ 108 and 107 W/cm2 at exposure times of ~ 50 and 100 ns, respectively. The number of pulses N varied in the range from 10 to 30. The rate of evaporation and radiaсtive sputtering changed slightly with an increase in the number of pulses of energy flows acting on the material and amounted to h ≈ 0.01 – 0.02 μm/puls. The irradiated surface after repeated melting under the action of a pulsed radiation-thermal load with powerful energy flows acquired a wave-like character with inclusions of dispersed micro particles of the second phase, containing mainly yttrium, oxygen, aluminum, iron, and titanium. At the same time, in contrast to the refractory metals (W, Mo, Ti) earlier under similar radiation conditions studied, no micro- and macro cracks were formed on the surface of the material facing the plasma. “Vikhr” Plasma Focus setup proved to be an effective tool for simulation testing of candidate materials with magnetic and inertial plasma confinement.
The features of the destructive effect of high-pressure generated under comparable conditions, namely, upon irradiation of target samples with pulsed laser radiation and beam-plasma flows created in Plasma Focus (PF) devices, on metal materials were studied. In both cases, close parameters of radiation-heat treatment were provided: power density q ~ 1010–1011 W/cm2 and pulse duration τ ~ 10 –100 ns. It have been shown that the double exposure of laser radiation to thin samples of vanadium and molybdenum with a thickness of 0.3 mm and 0.1 mm, respectively, leads to the formation of molten zones in the materials, inside which there were deep craters. The craters extended over the entire thickness of the samples, on the reverse side of which the recesses end with holes of ~ 0.1 mm for V and 0.2 mm for Mo. In a tungsten sample 0.2 mm thick, the depth of the craters in the molten zone was less than its thickness and there were microcracks on the back of the sample. Based on numerical estimates of the process under study, it was suggested that the observed effects are associated with the creation of high pressure zones of ~ 1 – 10 GPa in the irradiated targets, localized in microregions of radius r ~ 0.1 mm. In these zones, the behavior of the solid phase of the target materials, for which the tensile strength σB ≤ 1 GPa (V, Mo, W), under high pressure became close to the behavior of the liquid. The pseudo-liquid phase of the material was displaced from the center of the crater, where the pressure was maximum, to its periphery to the region of low pressure with the subsequent release of matter from the target through the irradiated surface at a speed of ~ 103 m/s. In experiments using the PF, the mechanism responsible for the formation of craters when a powerful pulsed laser radiation is applied to the target is not realized due to the different nature of the distribution of the absorbed energy density in the surface layer of the irradiated sample. The region in which the energy absorbed during the of particles implantation into the material was determined mainly by the average energy and the diameter of the ion beam (Еi ≈ 100 keV, d ~ 2 – 10 mm) and exceeds by one or two orders of magnitude the corresponding volume under laser irradiation.
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