Dynamics of accelerated compact toroidal plasmas

Previous work on the RACE experiment has demonstrated acceleration and focusing of spheromak-type compact toroids of low mass (10 μg), low density (1013 cm-3), and low magnetic field (2 KG). Computer modeling and measurements give reasonably good accounting of ring mass, momentum, and energy. Present work has been toward increasing the ring magnetic field and utilizing inductive storage by compressing similar plasma rings prior to acceleration. The precompression, followed by acceleration has been performed. Ring density and magnetic field have increased (ne ∼ 10 15 cm-3, B ∼ 4 KG) in the precompression cone, and magnetic field increases (B ∼ 8--12 KG) after compression and during acceleration, however, trajectory measurements have shown an increase in drag or possibly ring mass above that accounted for by the density measurements in the precompression cone. For the low mass/density/field rings, drag forces did not need to be invoked for agreement between modeling and experiment and mass was consistent with electron density measurements. Drag and/or mass change is now apparently important in this higher mass/density/field regime