Optical studies of metal ceramic cathode

Abstract

Optical studies of metal ceramic cathode demonstrated that the intensity of plasma light emission of the surface of the MC plate before the current maximum was below the sensitivity threshold of the 18ELU photoelectric intensifier, despite the presence of plasma sufficient for the significant magnitude of the amplitude (up to 500 A) and growth rate of the beam current (up to 20 A/ns).This confirms that the feature of the plasma occurring on the surface of the MC plate is a large emission surface at low density, the light emission of which cannot be recorded by the photoelectric intensifier, except in cases of significant current growth and current density at small anode–cathode distances and with a trimmed MC plate.Measurements of the plasma light emission spectrum of the MC cathode showed that emission plasma is generated during discharge, both from stainless steel particles and from the ceramic base material, with traces of strongly ionized ions presumably visible. This confirms the significant impact of processes occurring precisely in the gap around the metal particles on the MC cathode operation.Studies using an electron-optical converter showed that the separation of plasma from the surface of the MC plate occurs at a rate of more than 2.5 cm/μs. It is shown that the amplitude of the pre-pulse for various high voltage pulse shaping circuits of accelerators was impact on kinetics of plasma formation and light emission on the MC cathode.