Study on Ignition and Electron Emission Characteristics of Inductively Coupled Plasma Cathode

Abstract

The inductively coupled plasma cathode (ICP/C) has been developed as electron source for ion thrusters to liberate the thrusters from the limitations of hollow cathode, such as the lifetime limit. Therefore, in order to improve the power consumption efficiency of the ICP/C, its ignition and electron emission characteristics were investigated experimentally as functions of orifice dimensions and ion collector shape in this study. It is obtained that the factors affecting its plasma ignition are not only the applied RF voltage and the vessel inner pressure but also the conditions in the vessel. Its ignition capability is enhanced with increasing the orifice length and decreasing the orifice diameter because the inner pressure increases at constant xenon mass flow rate. On the other hand, there exists an optimum diameter of orifice for electron emission performance of the ICP/C. Additionally the pole collector is preferable to the cylindrical collector for electron emission. When the pole collector was inserted in the cathode, the typical performance was 0.48 A of the anode current at 24 W of RF power, 0.10 mg/s of xenon mass flow rate and 40 V of anode voltage.