[20a-A105-1~8] 8.1 Plasma production and diagnostics

[20a-A105-1] Characterization of an Electron Source with Cerium-Iridium Alloy for Spacecraft

〇Hiroki Watanabe¹, Shinatora Cho¹, Yoshiki Matsunaga¹, Yasushi Ohkawa¹, Yuki Tao², Takayuki Hirano² (1.JAXA, 2.KOBELCO Res. Inst.)

Keywords:plasma cathode, electric rocket propulsion, cerium-iridium alloy

Hollow cathodes are typically used as electron sources in ion and Hall thrusters to ionize propellant and neutralize the ion beam. A plasma is generated within the hollow cathode through thermionic emission. We propose to use iridium-cerium alloy (CeIr₂) in the thermionic emitter of a hollow cathode. A 1,000-hours endurance test of a hollow cathode with a CeIr₂ emitter was conducted to characterize the emitter degradation. The deposition and modification on the emitter inner surface were not evident after the test. Effects of temperature and partial pressure of oxygen on thermionic currents emitted from CeIr₂ were measured in diode configuration to evaluate work function and poisoning characteristics of CeIr₂. The work function of CeIr₂ was lower than that of lanthanum hexaboride (LaB₆) and higher than that of tungsten impregnated with barium and calcium oxides and alumina. In addition, the resistance of CeIr₂ to poisoning was comparable to that of LaB₆. More experimental results and discussion will be provided in the 83rd JSAP Autumn Meeting 2022.