Cathode jets and the retrograde motion of arcs in magnetic fields

Abstract

The influence of a transverse magnetic field on the jets of an impulse discharge was investigated. It was found that the jet trajectories show a curvature. The amount of the curvature depends on the pressure, the magnetic field intensity, the discharge current, the material and the polarity of the electrodes.

The curvature of the jets was explained as a result of the action of forces arising in a plasma flow through a magnetic and electric field; their analysis was carried out on the bases of a MHD model.

On hand of a derived solution, a possible influence of the jets on the origin of a retrograde motion is discussed. It is shown that the existence of certain discharge parameters and of a certain magnitude of the magnetic field brings about, in a plasma flying through a magnetic field, an induction of fields and currents under the action of which, on the one hand, the plasma itself flows in a retrograde direction and, on the other hand, there are influenced the trajectories of the carriers (particularly those of ions) of the current in the channel of discharge in front of the cathode spot. The proposed model of the retrograde motion is discussed and compared to the known results.