Plasma-RF Coupling in Electrodeless Plasma Thrusters for in-Space Propulsion

Electrodeless plasma thrusters (EPTs) are a novel technology in which a plasma is generated and heated by radiofrequency fields. The plasma then expands quasineutrally in a magnetic nozzle, without the need of a neutralizer. We present the recent developments of two EPT prototypes at UC3M: a helicon plasma thruster (HPT, operating in the tens of MHz, around 500 W) and an electron-cyclotron resonance thruster (ECRT, GHz range, 80–300 W). We describe the hardware employed for RF generation, amplification, and matching in each case, the mechanisms for propagation and absorption of the electromagnetic waves in the plasma in these devices, the laboratory experiments, and their results. We also report on the latest modeling efforts to solve the plasma-wave interaction problem numerically.