Structural Changes in Surface Layers of Vanadium Induced by the Separate and Sequential Impact of Helium Ions and Pulsed Laser Radiation
Changes in the morphology of the vanadium surface as a result of separate and sequential action of helium ions (energy-30 Kev, dose - 1.0 × 1022 m-2 , ion flux density – 4,8 × 1018 m-2 s-1 , temperature ~ 500 K ) and high-power pulsed laser radiation in the modulated q-factor mode (power density q = 1.2•108 W/cm2, pulse duration τ0 = 50 ns, the number of pulses N from 1 to 4) were investigated. It was found that the effect of laser irradiation on vanadium samples before and after ion implantation is identical (the formation of a hole surrounded by a breastwork, which occurred during the splash of molten metal), but in the case of preliminary introduction of helium into the material, the metal splash is more intense. Helium implantation into the samples causes radiation blistering, and the subsequent impact of laser pulses increases the erosion of the material in the zone located directly behind the hole (an increase in the number of exfoliated layers, the merger of blisters, etc.), which is due to sufficiently high temperatures in this area even after the termination of the laser pulse. Under real reactor conditions, this can lead to an increase of plasma contamination.