Effect of the expanding explosive-emission centers plasma on theimpedance of a high-current diode

Formulas for the space-charge-limited electron current in a planar diode with a small hemispherical or hemi-cylindrical plasma emitter have been obtained theoretically and by a numerical simulation. For a periodic cathode structure of hemispherical emitters, an approximate expression for current is derived. Based on these results, the increase in current with time in high current explosive-emission diodes is explained. A condition has been found under which the expanding cathode plasma has no effect on the diode impedance. This is related to the electric field pressure on the cathode. A configuration of the cathode surface has been proposed which provides realization of this condition