A PHYSICAL MODEL OF THE LOW-CURRENT-DENSITY VACUUM-ARC

A one-dimensional (1-D) physical model of the low-current-density stea dy-state vacuum are is proposed. The model is based on the continuity equations for ions and electrons and the energy balance for the discha rge system; the electric potential distribution in the discharge gap i s assumed to be nonmonotonic. It is supposed that the ion current at t he cathode is generated within the cathode potential fall region due t o the ionization of the evaporated atoms by the plasma thermal electro ns having Boltzmann's energy distribution. The model offers a satisfac tory explanation for the principal regularities of a hot-cathode vacuu m are with diffuse attachment of the current. The applicability of the model proposed to the explanation of some processes occurring in a va cuum are, such as the flow of fast ions toward the anode, the current cutoffs and voltage bursts, and the backward motion of a cathode spot in a transverse magnetic field is discussed.