Robert B. Sheldon and Scott Spurrier
March 9, 2001
Physics Dept., The University of Alabama in Huntsville, Huntsville, AL 35899
The observation of 40 keV field-aligned plasma flows, [Sheldon et. al., 1998] has been conjectured as the result of a space-charge driven instability generating kV parallel potentials [Sheldon, 1999], which occur whenever hot plasma drifts in an inhomogeneous magnetic field. Such conditions occur in almost any magnetic field that interacts with an energetic plasma; at the Earth, the Sun, Jupiter, and perhaps even astrophysical magnetospheres of stars, black holes and active galactic nuclei, all of which possess collimated flows. From this ubiquity, we have looked for field-aligned flows in a table top plasma experiment involving a permanent magnet and a DC discharge source of energetic plasma. We emphasize that a one-fluid plasma theory such as magnetohydrodynamics is incapable of describing a parallel potential drop, and that most second order corrections to the theory predict weak parallel voltages proportional to the thermal energy. In contrast, we show photographs of the plasma and peculiar high-voltage ( 500eVkT) discharges suggestive of a large field-aligned potential drop. We propose that this may be a manifestation of the Quasi-Neutral Catastrophe heretofore neglected by space and laboratory plasma physicists, which may unify many disparate observations.