Investigation of charge balance in diode unit of pulse electron accelerator

Abstract

The results of experimental research of charge balance in the diode unit of high-current pulsed electron accelerator TEU_500 (350...500 keV, 60 ns, 250 J per pulse) at the operation of electron beam generation are presented. The investigations are performed for the planar diode as with the cathodes made of graphite, copper, carbon fiber 43...60 mm in diameter so with the multi-edge cathode. It is shown that the main source of parasite losses of electrons in the planar diode is their scattering in the anode-cathode gap induced by the electron field distortion at the cathode periphery. In the matching mode of diode impedance to the output resistance of nanosecond generator (gap of 10...12 mm) the charge losses value does not exceed 12 %. The half of electron scattering angle is 68° at small anode-cathode gaps and it decreases with the gap increase down to 60°.