Operating Characteristics of Hall Thruster with Radio Frequency Plasma Cathode

Abstract

Radio frequency (RF) plasma cathodes have been researched and developed as an electron source to remove the drawbacks with dispenser hollow cathodes from ion and Hall thrusters. In this paper, we evaluate the electron-emission performance of a RF plasma cathode and the operating characteristics of the combination of a 1-kW class anode-layer-type Hall thruster and the RF plasma cathode. For the RF plasma cathode, an anode current of 3.5A is obtained at an RF power of 140W, a xenon mass flow rate of 0.2mg/s. The anode current is sufficiently high to operate the Hall thruster. Normal ion beam extraction and neutralization for the combination were experimentally confirmed. The anode efficiency of the RF plasma cathode is comparable to that of a hollow cathode. Based on this result, the feasibility of the RF plasma cathode for the Hall thrusters in ground tests was confirmed. However, because of the high RF power consumption, the total efficiency of the RF plasma cathode is lower than that of the hollow cathode at anode mass flow rates of 2.0mg/s and 2.9mg/s. This result indicated that for space-related applications, it is important to reduce the power consumption of RF plasma cathodes.