Origin and confinement of energetic ions in a multidipole plasma

In his current program of research the author employs a multidipole plasma device as an ion source for cross field ion beam-plasma experiments. In assessing initial beam parameters he was also faced with the paradoxical observation of eV ion energy dispersions. Although the sensitivity of his diagnostics (wave measurements, planar gridded electrostatic analyzers, Jones (1978), and ion sensitive probes) could be at fault another explanation seemed possible. Since he knew that his source plasma density was inhomogeneous and fell off toward the extraction grid it seemed plausible that the plasma potential might also be nonuniform. The author concludes that superthermal electron streams establish space charge fields which act to heat and confine plasma ions.