Effect of the angular distribution of cathode ions on the current flow in a high-current vacuum arc

The effect of the angular distribution of cathode ions on the parameters of a vacuum arc is investigated. It is shown that, at current densities characteristic of a high-current arc, collisions of flows of fast ions from different cathode spots may result in a high value of the ion temperature at the cathode plasma boundary. The boundary in current density of the region of a stable current flow as a function of the width of angular distribution of cathode ions is determined. It is found that, in the region of supersonic flow of ions, the permissible value of the current density drops rapidly as the angular distribution width increases, and in the subsonic region, it rises rapidly. An expression is obtained for the maximum possible ion sound velocity and for the equivalent critical ion velocity. Two- and three-fluid hydrodynamic models are used to perform calculations that illustrate characteristic distributions of parameters in the discharge gap. Analysis of the calculation results makes it possible to discuss the characteristic features of current flow in a vacuum discharge.