Study on Radio Frequency Cathode for Ion Engines

Abstract

A new cathode with inductively coupled plasma for ion engines was designed and then evaluated experimentally in this study. The fabricated cathode, which named “ICP/C (Inductively Coupled Plasma Cathode)”, employed electromagnetic fields induced by RF (Radio Frequency) current at 13.56 MHz, and had the new ignition method that spark discharge occurred by induced voltage was used. Through the experimental investigations, the new method using “C-shaped” type electrode enabled the ICP/C to ignite instantaneously without other electron source. And the cathode achieved high neutralization performance, which was over 1700 mA of extracted electron current at 80 W of RF input power, and 3.0 sccm of Xe flow rate, when target voltage simulating ion beam was 20 V. Additionally, the application of ICP/C as a main cathode of direct current ion thruster was confirmed. As these results, ICP/C may permit instantaneous ignition and simple handling to ion engines, and it may even allow a longer lifetime of ion engines.