Acceleration of background gas ions triggered by interactions of cluster targets with intense laser pulses

In the laser-driven ion acceleration using cluster-gas targets, consisting of a few hundreds nanometer sized clusters and the background gas, the energy spectrum of accelerated ions has two components. The lower energy components is produced by the Coulomb explosions of clusters and the higher one is composed of ions accelerated by electric fields created by the magnetic vortex. In this study, in order to understand the acceleration mechanism of the background gas ions, we have carried out numerical simulations using the 2D PIC codes. The simulation results shows that background gas ions are compressed and accelerated due to the Coulomb explosion of clusters. (author)