Expansion of a negative ion plasma into a vacuum

Abstract

The expansion of a plasma consisting of positive ions, negative ions, and electrons into a vacuum is solved numerically. In addition to the expected self-similar expansion found in a quasineutral plasma expansion model, a burst of positive ions is accelerated into the vacuum and a burst of negative ions is accelerated into the plasma. These accelerated ions arise since quasineutrality is not imposed in the simulation.