Collisionless electrostatic shock generation and ion acceleration by ultraintense laser pulses in overdense plasmas

Collisionless electrostatic shock (CES) generation and subsequent ion acceleration in laser plasma interaction are studied numerically by particle-in-cell simulations. Usually a CES is composed of a high ion density spike surrounded by a bipolar electric field. Ions in front of it can be either submerged or reflected by the shock front. The submerged ions experience few oscillations before becoming part of the shock itself, while the reflected ions are accelerated to twice the shock speed. The effects of the target thickness, density, ion mass, preplasma conditions, as well as the laser intensity on the shock generation are examined. Simulations show that such shocks can be formed in a wide range of laser and target conditions. The characteristic of the shock propagation through a plane interface between two targets with different properties is also investigated. These results are useful for future experimental studies of shock generation and acceleration. (C) 2007 American Institute of Physics.