SELF-CONSISTENT CHARGED-PARTICLE MOTION IN NEGATIVE-ION PLASMAS

The self-consistent one-dimensional kinetic theory of relaxation of a low pressure quasineutral negative-ion plasma destroyed in a limited r egion by a powerful laser light pulse is developed. Using the self-sim ilar method, well known in hydrodynamics, we examine the counterflow o f the negative plasma species and show the important role of the self- consistent electric held. The negative-ion temperature determined from the ballistic model is valid when the ratio of negative-ion to positi ve-ion densities is lower than 0.1. The overshoot of electron density that was observed experimentally is described by this method. We show that the overshoot can disappear when the positive-ion mass or tempera ture goes up. The self-similar solutions are also supported by numerou s experimental results.