The interelectrode discharge characteristics of the electrospray-type thrusters

Abstract

In order to study the interelectrode discharge characteristics of the electrospray-type thrusters, an electrospray model and a test system have been established. The experiments are carried out with a variable pressure discharge of 6 × 10−3 Pa to 8 × 104 Pa at a polar spacing of 1.5–3.0 mm. The physical explanations of breakdown voltage, threshold current, breakdown voltage waveform, and frequency variation with pressure are discussed. Various electrical field behaviors between electrodes at specific pressure and voltage ranges are analyzed. The results show that the breakdown voltage characteristic curve of the polar spacing presents a typical minimum characteristic, and the breakdown voltage of the electrospray model can be significantly improved by reducing the pressure below 10−1 Pa. The emission current of the vacuum working area is larger than that of the near-atmosphere working area, and the threshold current of the failure area is very low. The breakdown voltage waveform is periodic and changes abruptly at about 20 Pa. Before the mutation, the breakdown voltage frequency is inversely related to the pressure and the polar spacing. After the mutation, it is positively linearly related to the pressure and inversely related to the polar spacing. With the reduction in air pressure, different forms of discharge occur between the electrodes. Before the breakdown, corona discharge and dark discharge occur in turn. After the breakdown, spark discharge, arc discharge, glow discharge, and vacuum spark discharge all occur in turn.