Numerical simulation of the motion of cathode spot system on a planar electrode in magnetic field

Abstract

The present work, which continues the work [1], deals with simulation of cathode spot (CS) motion in the self-consistent magnetic field (MF) in the 3D formulation. Plasma jets are modeled as cylinders of a small radius, their conductivity depending on the MF. Electrodes are modeled in their actual 3D geometry. The magnitude and direction of the velocity of the CS motion versus the MF components is taken from the experimental data on the motion of a single CS [2]. The dependence of the cathode jet conductivity on the MF is found by means of interpolating the Volt-Tesla characteristics (VTC) for a single CS from the same work. Use is made of the mechanism for CS splitting upon exceeding some threshold in the current and CS destruction at currents lower than another threshold. The attaining of the steady state by the voltage across the discharge was studied and found to take place after the CSs reach the electrode edge. The temporal dependences of histograms of CS distribution in the current were derived. The obtained results are used to plot the VTC of a CS system. The qualitative behavior of the dependences agrees with experiment, which is an argument in favor of the assumption of the behavior of a high-current arc to be determined to a large extent by that of a system of individual CSs, interacting via the common self-consistent MF.