Minihelicon Plasma Thruster

A compact high-power-density helicon plasma source operating on abundant medium atomic weight gases is under examination for a potential electric propulsion application. A high specific impulse, which is easily varied in the range of similar to 1-2 ks for Ar and similar to 2-4 ks for N-2 propellant, was achieved. A well-collimated plasma plume with emittance similar to 10 degrees. is produced in a single-magnet configuration. Analysis of the data obtained using in situ and noninvasive spectral diagnostics indicates almost complete gaseous propellant ionization and thrust efficiency eta T similar to 20% with the lowest net ionization cost of similar to(80 V)(-1) per ion. Direct weighing has yielded a thrusting force of T similar to 10 mN.