Laser Absorption by Coulomb Collision

Abstract

When intense lasers are irradiated on any kind of material, the electrons near the material surface are emitted into vacuum, and ionization is triggered by strong laser field. Brief summary of such multiphoton ionization is given to explain how laser interacts with formed plasma. After deriving the Coulomb collision coefficients of thermal plasma, the laser absorption rate is derived for collisional plasma. Energy transfer from laser to electrons are consequences of many of nonadiabatic interaction of electrons with ions. The laser absorption coefficient is derived by three methods, from random walk model, quasi-linear diffusion model, and Dawson-Oberman kinetic method. The last one is very mathematical and exact, while it is shown that the former two based on simple models results also good result with well understandable intuitive view.