A new mechanism of laser absorption in a sputtered thin plasma

This paper discusses the laser absorption in a thin underdense plasma layer , which is sputtered from a solid surface ablated by laser irradiation. An analysis expression of absorption efficiency is obtained, and two new absor ption mechanisms are revealed. The first one is an unusual, but effective, wave-particle resonance absorption (which is different from the conventiona l Landau damping). The second one is a new, but much feeble, effect of the density and velocity gradient on the laser absorption. Enhancement of the s puttered velocity will increase the absorption efficiency of the laser, but non-homogeneity of the plasma will decrease it.