Switching vacuum arc in a pulsed transverse magnetic field

An experimental analysis of the vacuum arc behavior in a pulsed transverse magnetic field with amplitudes up to 120 mT and frequency of 900 Hz is presented in the paper. The arc was produced between Cu contacts during the switching-off operation of the current half-wave of amplitude 500 A and frequency of 30 Hz, so that the circuit parameters had rather moderate values which are easy to obtain in a vacuum switch. The presented results are a part of work which aims to examine the possibilities of using transverse magnetic fields to force a current interruption in vacuum. The analysis was performed using high-speed photography (2000 frames/s) and a shielded Langmuir probe. The results obtained show that the plasma movement and the displacement of the arc in the oscillatory magnetic field proceed according to the Lorentz force acting on ions. This arc displacement is in accordance with the retrograde motion known from the literature, which is opposite to that resulting from the Amperian force. Arc voltage increases of up to about 80 V were observed during the magnetic field action, but the current flow remained undisturbed.