Characterization of helicon plasma thruster performance operated for various rare gas propellants

The simply designed, helicon plasma thruster consisting of the cylindrical source cavity and the magnetic nozzle are operated for various rare gas propellants, i.e., neon, argon, krypton, and xenon at the RF power of 1 kW, where the solenoid current and the mass flow rate are surveyed. The thrust is estimated from a displacement imparted by turning on the steady-state plasma and a calibration coefficient relating the displacement to the force, where the calibration coefficient is obtained before pumping down the chamber and confirmed to be unchanged after venting the chamber. When having similar RF power transfer efficiency no significant difference in the thrust is detected and the results are consistent with the electron diamagnetic thruster model. This fact suggests that the helicon plasma thruster is operational for any propellant species once if the RF power is efficiently coupled with the plasma, as both the major thrust components arising from the pressure term in the source and the Lorentz force in the magnetic nozzle can be expressed by the electron pressure.