STUDY OF FIELD-INDUCED EXPLOSIVE ELECTRON-EMISSION MECHANISMS OF PSEUDOSPARK SUPEREMISSION CATHODES

Various mechanisms of electron emission, including the field, field-en hanced thermionic, and explosive electron emissions from pseudospark c athodes, are discussed and compared, The mechanism of the field-induce d explosive electron emission due to microstructure on the cathode sur face is considered to be more likely the pseudospark superemissive mec hanism. A high-mean electric field up to 3-5 MV/cm on the cathode surf ace in the end of hollow cathode phase is enough to initiate the mecha nism, The cathode spot initiation delay time (<10 ns) and explosive em ission threshold current (similar to 10(8) A/cm(2)) prior to the high current conducting phase are given by solving the initial value proble m of the one-dimensional heat conduction equation, thus explaining the existing experimental data of the pseudospark cathode superemission. In the case of multigap discharge, the above mechanism occurs on nearl y all cathode and interelectrode surfaces, Experimental evidence in si ngle- and multigap pseudospark discharges supports the suggested expla nation.