535 / 2017-05-12 20:38:06

Numerical simulation of low-current vacuum arc in strong axial magnetic field taking into account the generation of secondary plasma.

vacuum arc,2696,axial magnetic field,hybrid model,sputtering

The plasma of high-current vacuum arcs in vacuum interrupters with axial magnetic fields (AMF) greater than 15-20 mT/kA consists of unmixed plasma jets emitted by separate cathode group-spots. Therefore, the study of such a separate plasma jet is important for understanding the operation of the interrupter as a whole. Such single plasma jets in a strong AMF have been extensively studied experimentally earlier. In these studies, it was shown that the secondary plasma, which appears mainly near the anode, plays an important role in the formation of such a plasma jet.
The present paper is devoted to computer simulation of the plasma jet emitted from one group-spot in a strong AMF, taking into account the secondary plasma arising from the sputtering of electrodes and the incomplete sticking of the incident ions. Using the previously developed hybrid model, the generation of secondary plasma and the interaction of the secondary plasma with the plasma emitted by the cathode spot were studied. It is shown that, because of these processes, a plasma jet in the interelectrode gap of several millimeters in size with the applied AMF is a plasma core surrounded by a halo of neutral atoms. The appearance of the jet calculated in the framework of the model is qualitatively consistent with the experimental data.