Applicability of the 1D Child–Langmuir relation for ion diode current calculation

Abstract

The paper presents the results of the analysis of the influence of curvature of the electrons trajectory in the anode–cathode gap of an ion diode on the diode impedance and evaluation of applicability of the one-dimensional (1D) Child–Langmuir (CL) ratio for calculation of the electron current. Investigations of an ion diode with a graphite anode in self-magnetic insulation mode were carried out. Experiments were performed on the TEMP-4M ion accelerator set in a double pulse mode, with the first negative pulse (150–200 kV, 400–600 ns) followed by the second positive pulse (250–300 kV, 150 ns). The result of this study is that we have determined the boundary conditions for the applicability of 1D CL ratio for calculation of the electron current in the ion diode. It was found that the deviation of the diode current–voltage characteristics from CL ratio will be observed only with a significant change in the acceleration voltage during electron drift or when the electron drift time exceeds the transit time of ions.