Influence of anode and cathode plasmas on the operation of an electronic diode with an explosive-emission cathode

The results of modeling and experimental investigation of the formation of anode and cathode plasmas in a vacuum diode with an explosive-emission cathode during the generation of a pulsed electron beam with a current density of 0.3–0.4 kA/cm$^2$ and an accelerating voltage of 300–500 kV are presented. It is shown that the concentration of the anode plasma does not exceed 10$^{10}$ cm$^{-3}$ and it does not significantly contribute to the operation of the diode. However, the complete desorption of molecules from the working surface of the explosive- emission cathode and the high efficiency of shock ionization of atoms ensure the formation of a cathode gas plasma with a concentration of $\approx$ 10$^{16}$ cm$^{-3}$. It is found that the charge of the explosive-emission plasma layer is significantly less than the charge of the electron beam and the main source of electrons is not an explosive-emission plasma, but a cathode gas plasma. In this case, the electron current is limited by the concentration of the cathode plasma. The use of a cathode with a developed surface (a cathode with a carbon fabric coating) allows increasing the total charge of the electron beam by more than 1.5 times without changing the cathode diameter and the anode-cathode gap.