Coulomb explosion and energy loss of fast C-60 clusters in plasmas

摘要

The spherical-shell model and the molecular dynamics (MD) method are used to simulate the interactions of energetic C-60 clusters with the high-density plasma targets within the framework of the linearized Vlasov-Poisson theory. While the shell model describes Coulomb explosions of randomly oriented clusters under the assumption of isotropic expansion, the MD simulations capture the role of the wake effect in the interionic forces due to the dynamical polarization of the plasma. We find that the vicinage effects in the cluster self-energy, the Coulomb explosion dynamics, and the stopping power are strongly affected by the variations in the cluster speed and the plasma parameters. For example, Coulomb explosions are found to proceed faster for higher speeds, lower plasma densities, and higher electron temperatures. Both approaches show that the cluster stopping power is strongly enhanced in the early stages of Coulomb explosions due to the vicinage effect, but this enhancement eventually diminishes, after the cluster constituent ions are sufficiently separated. This takes place after a penetration time, which is found to be shorter in the MD simulation than in the shell model, owing to the wake-induced elongation of the cluster structure in the course of Coulomb explosion. (c) 2005 American Institute of Physics.