Particle and power balance in a helicon operating with light gases [experiment]

Measurements of input power, particle flow, radiation, electron density profiles, plasma flow, and electron temperature profiles over a range of input power, magnetic field, and neutral flow were used to do a power and particle balance during operation with light gases H, D, and He in the VASIMR experiment at the Advanced Space Propulsion Laboratory. In addition, an axial pressure scan provided important information about the importance of charge exchange collisions. The pressure in the helicon increases about a factor of 4 when the helicon is turned on. We make the assumption that electron temperature is constant along the axis of the helicon. Several important observations can be made: 1) The electron density increases with power, 2) Plasma flow is important in determining plasma conditions, 3) Radiation losses are large, and 4) charge exchange processes are important.