A model of the cathode of a thermionic arc

Publisher Website
Google Scholar
Abstract
A theoretical model of the cathode of a thermionic arc is presented. Attention is focused on the energy balance of the electrode, with the interplay between the cathode and the arc plasma being described by boundary conditions specified on the electrode surface. Physical processes included in the model are thermal conduction and Joule heating in the electrode, radiative energy exchange between the electrode and the arc plasma, thermionic emission, and ion flow in the cathode sheath. A model of the cathode of a 100 A arc burning on tungsten in argon at atmospheric pressure is described in detail. It is shown that the flow of electric current and heat close to the tip of the electrode is controlled by thermionic emission and arc radiation, while the ion current plays a dominant role in the outer parts of cathode spot.