Droplet Formation on the Melt Surface under Heat Load Due to the High-Energy Electron Beams with Power Density Scale of Several MW/CM2

Abstract

Interaction of high-energy electron beams (~100kV) with metallic surfaces was investigated using high-resolution imaging diagnostics. During energy deposition with a power density of several MW/cm 2 , depending on the penetration depth of the electrons, there is intensive formation of drops of melted material, which leads to a significant reduction in the quantity of treatment. With the same power densities of other energy drivers such as laser beams, plasma jets in fusion reactors, high-current ion beams, the same effect is observed, which can be explained by the well-known instabilities such as Rayleigh-Taylor, Kelvin-Helmholtz, and capillary waves. Due to higher penetration depths of electrons, the thermodynamic conditions at the melt surface for the occurrence of such instabilities are not met. The temperature inversion in the melt layer is discussed as a probable mechanism of the droplet formation.