Ion-Mixing Mode and Model for Density Rise in Confined Plasmas

Abstract

A model for the rate of density rise observed when neutral gas is fed into the plasma chamber is presented for regimes where known collisional transport processes do not provide an adequate explanation. A dense layer of cold plasma produced at the edge of the plasma column and the resulting ion-temperature gradient, sharper than the relative density gradient, can lead to the excitation of electron temperature fluctuations driven by ion drift modes. These can induce a net inflow of electrons and ions under realistic conditions.