Generalized derivation of the Stamper term in the nonlinear force of laser plasma interaction

Though a general formulation of the nonlinear forces generated in a plasma by electromagnetic fields was derived in 1969, explaining several phenomena now observed, one special property evaluated recently is the term proportional to the collision frequency (Stamper term) for the case of plane electromagnetic waves perpendicularly incident on a stratified plasma. The authors derive this term generally as due to the collision term in the second Schluter equation (generalized Ohm's law) and find an additional term. Numerical cases show its importance for laser intensities very close to the threshold, above which the nonlinear forces are dominant over the thermokinetic forces.