Development and Demonstration of a Cathodeless Electron Cyclotron Resonance Ion Thruster

The electron-cyclotron-resonance microwave-discharge ion thruster system utilizes no cathodes to emit thermionic electrons for plasma generation in both the ion source and the neutralizer. The ion source can generate xenon ions at an ion-production cost of 300 eV and a propellant utilization efficiency of 88 %, with a double-charged-ion population of 8 %. The neutralizer can output 100 m A of electron current with 10 W of microwave power and 0.5 seem of xenon flow. The thruster system combining the ion source and the neutralizer operated for 300 h without detectable erosion of the screen grid and ion source. Except for the primary frequency of 4.2 GHz used to generate plasmas, the system proved experimentally compatible with spacecraft electromagnetic interference requirements in the microwave frequency range.