Flow measurements by using Mach probe in unmagnetized plasmas

Abstract

Despite frequent usage of Mach probes in strongly magnetized fusion plasma, measurement of flow in unmagnetized plasmas, such as ExB shear flow, space propulsion and processing plasma remains to be developed further. We have measured plasma flows in various unmagnetized plasma sources, such as the Hanbit device of magnetic mirror, a dc plasma torch, a rf plasma and a rf plasma with supersonic ion beams. The measured data have been analyzed by using kinetic theory and PIC code simulation for unmagnetized plasmas. However, these kinetic and PIC simulation results do not include all experimental conditions, there have been some needs on Mach probe theory modifications. In this presentation, the applicable range of these theories will be reviewed and the measured Mach probe data will be reanalyzed considering collisions and low ion temperature (Ti=0.01Te) effects, which has not been included in the previous unmagnetized Mach probe theories.