Supersonic Motion of Vacuum Spark Plasmas along Magnetic Fields

Abstract

Studies of plasmas produced by sparks in vacuum are reported. The observations of principal interest concern the speed with which such plasmas leave the spark. The conclusions about plasma speeds are that they are approximately ten times greater than the thermal speeds associated with spark temperature, varying between 2 × 10⁶ and 2 × 10⁷ cm/sec, and in the range observed, the velocities are approximately independent of the spark parameters. It is suggested that the pinch effect may be the mechanism of plasma acceleration.