Negative ion plasmas

Abstract

In a plasma composed of negative (SF−6) ions, positive (Ar+) ions, and electrons (with ne/n+ reducible to less than 10−3) a fast ion mode (vph≈9Cs), due to the out-of-phase motion between positive and negative ions, is observed with reduced spatial attenuation. This fast ion mode exhibits spatial growth in the presence of a fast ion beam. Diffusion properties of the negative ion plasma are also presented.