Switching of the Vacuum-Arc Discharge Direct Current

Interruption of the direct current of a vacuum-arc discharge (VAD) is analyzed with three methods: the connection of a shunt circuit with a capacitor to the discharge chamber, the overlaying of a pulse nonhomogeneous axisymmetric magnetic field upon the discharge, and the combined action of the magnetic field and the shunt circuit. The probability of interruption of the current $I=500$ A as a function of the magnetic field induction is obtained for various shunt capacitances within the range $25\le C\le2500$ microfarad ($\mu\mathrm{F}$). It is shown that the probability of interruption for a given magnetic field induction increases as the capacitance is raised and for the given capacitance it increases as the induction is increased. The magnitude of the magnetic system current $I_m$ to ensure the current interruption with the probability $P=1$ is obtained as a function of the shunt capacitance. The impact of the shunt circuit parameters upon the arc current is analyzed. The time-domain plot of the arc current for the shunt capacitor $C=2500$ $\mu\mathrm{F}$ was estimated. Its results agree with the experiment. It is shown that the combined use of the magnetic field and the capacitive shunt circuit is an effective method of VAD direct current interruption.