Nonlinear density expulsion and electron heating in the nonadiabatic regime, and application to Ion Bernstein Wave heating

In the limit where a strong parallel electric field has short parallel scale lengths, the parallel electron motion becomes nonadiabatic and highly nonlinear, and the usual ponderomotive treatment of the slow time scale behavior of electrons is invalid. Were, a new nonadiabatic model for describing the resulting heating and expulsion of electrons from regions of a strong electric field is developed. The model shows that a typical electron is heated to a value characterized by the ''quiver'' velocity in the applied field. A nonlinear density expulsion still occurs in this nonadiabatic strong rf field limit, but exhibits an algebraic dependence on the wave amplitude in contrast to the exponential dependence that occurs in conventional ponderomotive theory. Results are applied to electrons in the edge plasma, near a high-power Ion Bernstein Wave heating antenna. (C) 1997 American Institute of Physics.