Electron energy spectrum in circularly polarized laser irradiated overdense plasma

A circularly polarized laser normally impinged on an overdense plasma thin foil target is shown to accelerate the electrons in the skin layer towards the rear, converting the quiver energy into streaming energy exactly if one ignores the space charge field. The energy distribution of electrons is close to Maxwellian with an upper cutoff εmax=mc2[(1+a02)1/2−1], where a02=(1+(2ω2/ωp2)|ain|2)2−1, |ain| is the normalized amplitude of the incident laser of frequency ω, and ωp is the plasma frequency. The energetic electrons create an electrostatic sheath at the rear and cause target normal sheath acceleration of protons. The energy gain by the accelerated ions is of the order of εmax