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

Physics of Plasmas, Volume 27, Issue 12, December 2020. 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.