Structure of intermittent variation of floating potential in a converging field following a magnetic beach ECR plasma source

Abstract

In converging field configuration of cylindrical plasma following electron cyclotron resonance plasma source, intermittent variation of floating potential, which is a negative spike with about ten microsecond duration, is observed. The event is ubiquitous; independent of measurement position and magnetic field. Cross correlation analysis for two floating potentials at separate positions reveals that strong correlation exists within the event timescale. The correlation along the magnetic field line suggests axially elongated structure. Radial extent of the structure is clarified by the radial correlation profile. Different FWHM of the radial profile at the plasma production region and the downstream converging field region is essentially explained by field line tracing.