Operating efficiency of planar diode with explosion-emission cathode at delay of plasma generation

Paper presents the results of the comparative analysis of the current and energy balance within a diode unit of a heavy-current pulse electron accelerator (350-500 keV, 60 ns, 250 J within a pulse) equipped with an explosion-emission cathode made of graphite, copper, carbonic material and with a multipoint copper cathode. In spite of the delay of formation of plasma surface in the cathode the planar diode with one-piece cathode (either a graphite or copper one) is shown to ensure the high efficiency of the conversion of the supplied energy into the kinetic one of the electrons (over 90%). When the planar diode impedance is matched with the output resistance of the nanosecond generator the diode operation efficiency does not depend on the time period of plasma formation in the cathode. Delay of plasma formation when applying a graphite cathode reduces the portion of the low-energy electrons within the generated electron beam and reduces electron losses in the anode foil when a beam is supplied from the vacuum space of the diode chamber to the reactor