NONLINEAR STOPPING POWER OF IONS IN PLASMAS

The study of the nonlinear stopping power of ions in plasmas is of fun damental importance for various applications. One example is the energ y loss of heavy ions passing through a plasma. Due to the high non-equ ilibrium charge states specific to heavy ions, the plasma regime with coupling parameters 1/N-D < 1 and Z(p)/N-D greater than or similar to 1 (N-D similar to number of electrons in a Debye sphere, Z(p) charge o f the ion) is of interest. In this regime, the Vlasov-Poisson system c annot be linearized, rather a fully nonlinear,treatment is required. I n the present paper, the Vlasov-Poisson system is solved numerically b y using the capability of the new generation of massively parallel sup ercomputers. The results are compared with the standard dielectric the ory and a recent binary collision approach. It is demonstrated that no nlinear effects lead to a strongly reduced Bragg-peak for Z(p)/ND grea ter than or similar to 1. In the nonlinear regime, the scaling of the stopping power is close to a Z(p)(3/2) law, which is found to be chara cteristic for the nonlinear stopping power, if the influence of close collisions on the induced potential is treated properly. (C) 1996 Amer ican Institute of Physics.