DC vacuum breakdown in an external magnetic field

TL;DR

This paper investigates how external magnetic fields influence vacuum breakdown and dark current, combining theoretical generalizations of the Fowler-Nordheim equation with experimental validation showing magnetic fields reduce breakdown voltage.

Contribution

It extends the Fowler-Nordheim model to include magnetic field effects and experimentally demonstrates the reduction in breakdown voltage caused by magnetic fields.

Findings

Magnetic fields decrease breakdown voltage by 10-20%.

Theoretical model predicts increased electron-impact ionization with magnetic fields.

Experimental results confirm the magnetic field's impact across various cathodes.

Abstract

The subject of the present theoretical and experimental investigations is the effect of the external magnetic field induction on dark current and a possibility of breakdown. The generalization of the Fowler-Nordheim equation makes it possible to take into account the influence of a magnetic field parallel to the cathode surface on the field emission current. The reduction in the breakdown voltage due to the increment in electron-impact ionization was theoretical predicted. Experimentally shown that the presence of a magnetic field about a tenth as a large as the cutoff magnetic field [18] reduces the breakdown voltage by 10% to 20% for practically all cathodes no matter what their surface treatment.