RF plasma production for Hall thruster diagnostic development and inhomogeneous RF field studies

A compact experimental platform for RF plasma production and diagnostic development has been constructed at the University of Alaska Anchorage, in which the target plasma emulates Hall thruster plasma conditions for the purpose of reconciling Langmuir probe measurements of electron fluid properties with non-invasive spectroscopic data. This allows the development and validation of a new collisional radiative model for argon plasma in which spectroscopic measurements lead directly to calculation of electron density and temperature. This capability will allow investigation of some open questions in Hall thruster plasma dynamics pertaining, for example, to electron transport across the thruster magnetic field. The platform uses a half-wave helical antenna driven at 13.56 MHz at up to 1 kW, and has the capability to introduce an axial magnetic of ~1 kG, allowing for helicon discharge modes as well as inductively coupled operation. Also, an array of parallel electrodes in a multipole configuration is investigated for capacitively coupled operation, density enhancement via RF multipole trapping, and plasma heating by inhomogeneous RF fields. In addition to these research aims, the platform is designed for easy access by undergraduate students conducting introductory through advanced plasma research projects and educational plasma laboratory experiments.