Vapor-cone angles of neutrals and ions emanating from the cathode of a dc mercury vacuum arc

Abstract

A stream of ions and neutrals emerges from the cathode of a vacuum arc discharge. Measurements made on a spot-anchored dc mercury vacuum arc show that, beyond the region of heavy-particle collisions, ions and neutrals are confined to the same circular vapor cone, and that the angle of this cone depends on the electron-to-atom emission ratio. This result is interpreted as indicative of the generation of the ions at the cathode spots in the form of highly directional vapor jets.