Suprathermal Electrons in Expanding Plasma of Vacuum Arc Jet

Numerical kinetic modeling of spherically expanding plasma with parameters characteristic of the plasma of the cathode spot of a low-current vacuum arc is performed. It is shown that under such conditions a group of electrons arises in the plasma, the energy of which practically does not change during expansion. As a result, at some distance from the cathode, the electron velocity distribution function in the direction of plasma expansion differs significantly from the drifted Maxwell distribution by the presence of a group of suprathermal electrons. The distribution function for velocities perpendicular to the direction of expansion remains Maxwellian.