Charge dependence of nonlinear stopping power

In heavy ion fusion the interaction process between heavy ions and matter under extreme conditions (i.e. high ion charge states, solid state densities and temperatures of hundreds of eV) is a topic of great importance for the target design. The consequent strong ion-target coupling cannot be fully described by the standard stopping power theories, as the dielectric and the binary collision approaches. We study the interaction of heavy ions with a classical plasma in regimes of strong nonlinear coupling by means of Particle-in-Cell (PIC) simulations. In this paper we focus on the charge dependence of the nonlinear stopping power. Our results are in good agreement with Vlasov simulations. We show that when the ion-plasma interaction process becomes nonlinear, the standard theories overestimate the energy loss. Nonlinear screening seems to explain in a simple manner our results. (C) 1998 Elsevier Science B.V. All rights reserved.