ENERGY-LOSS OF HEAVY-IONS IN STRONGLY COUPLED PLASMAS

We investigate the energy loss of heavy ions in strongly coupled plasm as, by performing molecular dynamics (MD) computer simulations. These studies are of interest in heavy-ion-driven inertial confinement fusio n, as well as for electron cooling. We consider the non-linear behavio r for strong target-ion coupling parameters, i.e. Z Gamma(3/2) greater than or similar to 1, in non-ideal plasmas with Gamma greater than or similar to 0.1 (Z is the charge number of the ion and Gamma is the pl asma parameter of the target). The new features that we found from our simulation results can be summarized as follows. (1) For strong ion-t arget coupling, the energy loss of the ions at low velocities scales w ith Z as Z(1.5), in agreement with recent experimental and other theor etical results. This clearly deviates from the Z(2) In(const./Z) scali ng of the conventional weak coupling theories. (2) The change in the Z scaling has its origin in a non-linear screening that occurs for stro ng coupling and is associated with an increase in the (static) screeni ng length above the Debye-Huckel result of the linear theory. (3) The non-linear screening is accompanied by electrons trapped by the ion in to high Rydberg states, through multi-particle collisions, Compared wi th the case of linear coupling, this trapping causes an enhanced elect ron density around the ion. (4) The transient time dependence of the s topping power after switching on the ion-target interaction has charac teristic time-scales that are a fraction of the plasma period.