Results on a 15-Joule theta-pinch FRC-physics test cell for space propulsion research

The U.S. Air Force Research Laboratory-Edwards has developed a new experimental test cell to study the physics of Field-Reversed-Configuration (FRC) formation, equilibrium, and acceleration at low-energy for space propulsion. The test-cell is compatible with a variety of plasma sources, including theta-pinch and rotating magnetic field sources. The first plasma source installed in the test-cell was a low-energy (15 J/pulse) theta-pinch source. This source has been tested at full energy with a xenon propellant and argon propellant at a range of fill densities (1-50 mTorr) and bias fields up to 1 kG. The test-cell was equipped with a suite of diagnostics to monitor plasmoid formation, include voltage and current transducers, an excluded flux array, internal magnetic field probes, emission spectroscopy, and Langmuir probes. Several pre-ionization schemes were tested with the source as well to investigate their effectiveness on plasmoid formation. Results on the theta-pinch plasma studies are presented here.