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

Formulas for the space-charge-limited electron current in a planar diode wi th a small hemispherical or hemi-cylindrical plasma emitter have been obtai ned theoretically and by a numerical simulation. For a periodic cathode str ucture 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 impedan ce. This is related to the electric field pressure on the cathode. A config uration of the cathode surface has been proposed which provides realization of this condition.