Spatially resolved measurements of plasma instabilities using a heavy ion beam probe

Abstract
A heavy ion beam probe has been used to obtain spatially resolved instability measurements in an energetic magnetically confined plasma. The amplitude and phase of both density and space potential fluctuations associated with a coherent 70‐kHz oscillation have been measured in a hollow cathode discharge. The measurements are made simultaneously from the same point in the plasma, are continuous in time, and have a spatial resolution element of <5 mm.