Amplification of separated electric charge field due to the capture of laser-produced fast electrons oscillating near thin target

Abstract

The effect of increasing strength of the electric field of separated charge due to the capture of laser-accelerated fast electrons in a thin solid target is theoretically substantiated. The target considered is so thin that a fast electron passes through the target during the time less than at least half of the applied laser pulse with the additional requirement that energy loss of a fast electron in the balk target is negligible compared to the energy transfer to ions accelerated in a sheath field. An analytical model is proposed of sheath field formation when fast electrons oscillate due to their reflections in the double layers at both boundaries of a thin target. It is shown that the increasing density of fast electrons inside the double layer and shortening of this layer are the reasons of sheath field strength amplification in a thin target in comparison with a thick target. The increase in the number and the energy of fast ions due to field amplification in a thin target is discussed.