Plasma measurements of the plume of a new miniature helicon thruster

Summary form only given. We present preliminary results of a campaign to characterize the ion acceleration mechanism of a new miniature permanent magnet helicon thruster. The magnetic field of the thruster´s neodymium magnets was measured to verify that the extent of the magnetic field and exhaust plume is small relative to our vacuum chamber (1 cubic meter). The magnetic field becomes comparable to the earth´s magnetic field (.5 G) about 50 cm from the thruster. Argon and xenon gas were used as propellants. Plasma properties of the exhaust plume were measured at various power levels (1-100 W) and propellant flow rates. Electron temperature and plasma density were measured with a double probe and a single Langmuir probe. The plasma potential was measured with an emissive probe using two methods: the floating potential in the limit of large emission and the inflection point in the limit of zero emission.