Preliminary Investigation of Electromagnetic Thrust Characteristics in Electrodeless Compact Helicon Plasma Thruster

In order to realize long-lived electric propulsion systems, we have been investigating an electrodeless plasma thruster. In our concept, high-density plasma from a compact helicon plasma source is accelerated by a magnetic nozzle for the thrust production. In order to optimize the thruster design, investigation of the thrust characteristics is needed. In this study, development of the electromagnetic thrust measurement system for compact helicon plasma thrusters and preliminary experiment of thrust measurement have been conducted. We have successfully developed a torsion-pendulum type thrust stand with measurement resolution of 10 N. From the thrust measurement, the electromagnetic thrust increases with the Ar gas mass flow rate and plasma production power. The thrust force and the electron density jump are observed due to the discharge mode transition from the inductively coupled plasma to the helicon wave excited plasma. The electromagnetic thrust force is up to 340 N (Ar gas mass flow rate of 1.0 mg/s, plasma production power of 400 W).