Movement, heating and evaporation of droplets in near-cathode region of vacuum arc

The report is devoted to theoretical research of process energy exchange of moving spherical macroparticles with scattering nonequilibrium plasma. The analysis of metal drops interaction with dense nonequilibrium plasma of a vacuum arc is carried out. Two cases are considered: 1) case of the rest plasma and 2) case of the fast expanding plasma. The theoretical estimation of a drop substance evaporation possibility during its flight through non-uniform cathode plasma jet is carried out. It is shown that under certain conditions significant and sometimes complete drops evaporation is possible. It is remarkable that the drops of more refractory substances can evaporate faster than drops of substances with low melting temperature (tungsten and gallium drops were investigated). The observable in experiments effect of a sudden appearance of luminous balls far from a cathode surface can be explained by sharp increasing of a drop temperature in the rest plasma.