Emission Parameters of the Cathode Spot Plasma During the Metal-to-Plasma Transition

The initial stage of explosive electron emission represents is of most interest in the case of production of subnanosecond and picosecond electron beams in devices with explosive-emission cathodes. In this work we have developed, based on the electron density functional theory, a self-consistent model that allows one to calculate the emission parameters of the cathode spot plasma in the range from the metal electron density to a density of ∼1018–1020 cm–3 in the interval of electron temperatures from zero to ∼5 eV. Calculations have been performed for a copper cathode. It has been shown that as the concentration of free charge carriers at the front the cathode flare is decreased from 1023 to 1020 cm–3, the work function of the plasma decreases to about one fifth. Thus, as the free carrier density decreases due to the expansion of the cathode spot plasma, the potential well for electrons practically disappears at ne ∼ 1020 cm–3. 1