Field-Reversed Configuration Thrusters
Schematic (left) of XOCOT system and photograph (right) of the XOCOT annular chamber, test setup, and current transmission cables.
FRCs originate from the nuclear energy community where similar devices are used to magnetically isolate and confine plasma for fusion purposes. In an FRC device, an azimuthal current is induced in a plasma (by rotating magnetic fields, for instance) in the presence of a steady axial magnetic field. The current reverses the axial field (hence the name “field-reversed”) which creates a well confined magnetically-isolated, high-density plasma body called a “plasmoid”. It is only in the last decade that FRCs have been investigated for thruster applications. Thrust can be achieved via the repeated, rapid formation and ejection of plasmoids. In addition to achieving the high Isp’s characteristic of electric propulsion devices, FRCs benefit from the plasma being magnetically isolated from the thruster hardware, thus limiting erosion. They can therefore also be used with a variety of propellants such as xenon, water, and carbon dioxide. Propellant flexibility is an attractive quality for missions employing in situ resource utilization (ISRU) technologies. There are several questions pertaining to the fundamental physics of FRCs. Currently at PEPL, there is an ongoing investigation of the scaling laws that govern the thrust mechanisms. Scaling laws provide valuable insight into how the thruster operates including how impulse and efficiency scale with input power. These laws will set the foundation upon which a thruster modeling and experimental campaign can be built.
Slough, J., Kirtley, D., and Weber, T., “Pulsed Plasmoid Propulsion: The ELF Thruster,” IEPC-2009-265, 31st International Electric Propulsion Conference, Ann Arbor, Michigan, September 20 – 24, 2009.
Hill, C., “Translation Studies on an Annular Field Reversed Configuration Device For Space Propulsion”, Ph.D, Michigan Technological University, 2012.
Little, J., Cornella, B., Pancotti, A., and Kirtley, D., “Scaling of FRC Thrusters with Neutral Entrainment,” AFRL-RQ-ED-TP-2016-302, 8th JANNAF Spacecraft Propulsion Subcommittee Meeting, Phoenix, Arizona, December 5 – 9, 2016.