The Influence of an External Coaxial Magnetic Field on the Characteristics of a High-Current ARC in a Vacuum Switch

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The influence of an external synchronous axial magnetic field on the characteristics of a vacuum-arc discharge is investigated within the range of discharge currents from 6 to 14 kA. The magnetic field amplitude is regulated in a wide range (from 0 to 190 mT) irrespective of the discharge current, while the specific magnetic field induction (in mT/kA) remains constant during the arc burning time. A critical specific magnetic field induction is determined, which prevents the discharge channel from constriction in the gap. It is shown that an application of an external magnetic field does not give rise to the formation of an anode spot, while the cathode is covered with a large number of microspots evenly distributed across its surface. An analysis of the probe currents demonstrates that the density of the post-arc plasma under these conditions decreases, and its decay is accelerated.