Investigation of changes in the field emission characteristics of the eroded cathode surface after submicrosecond vacuum arc discharges with different current amplitudes

Abstract

A multifactorial investigation of the influence of the parameters of a vacuum discharge on the copper cathode on its emission properties was carried out. The object of the study was the initially smooth surface of copper cathodes obtained by melting the tips of copper needles in vacuum. The typical radius of the cathode tip was 25–30 µm. Several cathodes were subjected to vacuum arc discharges of submicrosecond duration with a current amplitude in the range of tens of amperes. After each discharge, the cathode was placed in a field-emission projector inside the same vacuum chamber without breaking the vacuum conditions. An automated measuring system was connected to the projector to obtain the current-voltage characteristics of the field emission. According to the current-voltage characteristics, the factor of the electric field enhancement on the surface of the emitter was estimated. This estimation, in combination with the analysis of the images of the sample surface, obtained by the scanning electron microscopy, showed the increase of the characteristic size of the microrelief objects and the local electric field enhancement factor with the arc discharge current value.