The effect of external magnetic field on a vacuum arc

The effect of an external longitudinal magnetic field on the time required for anode spot formation in a high-current ($5$ to $12$ kA) vacuum arc is experimentally studied, and the minimal value of a magnetic field inhibiting the anode spot formation is determined. The experimental results are compared with theory. The phenomenon of break of current in a low-current ($100$ to $300$ A) vacuum discharge upon superposition of a magnetic field with transverse component on the discharge is investigated. The probability of break of current increases with the magnetic field. The possible mechanism of break of current is discussed.