Experimental investigation of graphite explosive-emission cathodes operating in a periodic pulse regime

We have studied the electron emission from graphite cathodes under the action of voltage pulses with an amplitude of up to 300 kV, a pulse duration of 10 −9 s, and a pulse repetition frequency of 1–3.5 kHz. The magnetically insulated electron beam had a peak power of up to 600 MW at an average power of 1–3 kW. The dynamics of emission current delay was studied in relation to the charge transferred by the beam and to the state of the cathode surface (studied by scanning electron microscopy). It is established that smoothening of the microrelief leads to degradation of the cathode emissivity, which can be compensated by increasing the pulse repetition rate above a certain critical level.