Research of Cathode Plasma Speed in Planar Diode With Explosive Emission Cathode

The research results of the speed dynamics of explosive emission plasma expansion in the planar diode with cathodes made of graphite, carbon fiber, and copper (solid and multiedged) and with the multiedged tungsten cathode are presented. The plasma speed was determined by the volt-ampere characteristics of the diode with a time resolution of 0.2 ns. The experiments have been performed at the electron accelerator TEU-500 (350-450 kV, 100 ns, and 10 kA). It was found out when the plasma formation at the cathode is completed, and until the pulse ends, the plasma speed is constant and equal to 2 plusmn 0.5 cm / mus for graphite and carbon fiber cathode, 3 plusmn 0.5 cm /mus for tungsten cathode, and 4 plusmn 0.5 cm / mus for cathode made of copper. The analysis of various mechanisms of anode plasma action on the deviation of electron current from the value described by the correlation of Child-Langmuir-reduction of anode-cathode gap, compensation of volumetric electron charge, and additional input of electrons and ions of anode plasma to the total diode current-has been performed.