INTERPENETRATION AND ION SEPARATION IN COLLIDING PLASMAS

The interpenetration of colliding plasmas in the transition regime, where the ion-ion mean-free path is of the same order as the gradient scale length, is studied by one-dimensional simulations and dimensional analysis. Separate fluid equations for multiple species are solved, with coupling between the different species due to the electric field and Coulomb collisions. These simulations show initial interpenetration followed by a "soft" stagnation. For colliding plasmas characteristic of opposing laser heated disks, the stagnation time, the stagnation density and temperature, and the interpenetration distance are shown to depend primarily on a single parameter, defining the ratio of the scale length to the ion-ion mean-free path. Simulations of colliding plasmas from exploding plastic foils with separate ion fluids for the carbon and hydrogen are presented, showing appreciable ion separation. These results may provide a guide for the design of interpenetrating plasma experiments. © 1994 American Institute of Physics.