Investigation of plasma rotation in a pulsed inductive accelerator.

Abstract

This paper describes an experimental investigation of the plasma properties in the accelerating current layer of a pulsed inductive plasma accelerator. Current from an initially charged capacitor passing through a flat spiral coil produces ionization and snowplow acceleration in argon at 1-torr pressure and room temperature without preionization. The plasma current layer forms in a thin disk increasing in intensity to a maximum of about 15 ka/cm2 after 0.2jusec. It then splits into two layers of reduced amplitude, producing a rounded shoulder on the corresponding magnetic field distribution. The plasma motion is calculated from electron density and electric and magnetic field measurements. There is an azimuthal velocity component showing that ions carry a substantial fraction of the total current in both of the current layers. The axial motion represents a kinetic energy on the order of 40% of the work done on the plasma by the accelerator coil during the first 0.6 jitsec of the first quarter-cycle at an average Isp of 1500 sec.