Discharge Mechanism of Mercury Pool Arcs

Abstract

A model for the discharge mechanism of mercury pool arcs is proposed and shown to be in agreement with experiment. The conclusions drawn from this model are the following: (1) Mercury pool arcs operate in the ball of fire mode of discharge. (2) The electron emission mechanism is nonthermionic. Emitted electrons from the cathode arrive with only thermal energies in a plasma adjacent to the cathode. The potential of this plasma is equal to or slightly higher than that of the Fermi level of the cathode. The emission may be either due to a large electric field at the cathode surface (tunnel effect) or due to an effective lowering of the cathode work function. This lowering of the work function may be caused by a vapor or plasma of high density adjacent to the cathode surface.