Kinetic model for plasmas in a strong high-frequency field

A kinetic model for stable, underdense plasma in the presence of a strong electromagnetic pump wave is presented. Ion dynamics are properly treated to account for enhancement in electrostatic fluctuations. Such fluctuations are important even for pump strength below threshold for the oscillating two-stream and parametric decay instabilities in the underdense region. Thresholds of these instabilities are numerically determined. The results of calculations for the static form factor S(k) electron collision terms, and the absorption coefficient are presented for stable, homogeneous plasmas. For moderate pump values (below instability threshold) enhanced fluctuation levels and increased absorption are found, which have relevance to a variety of experimental situations involving high-intensity laser, microwave, or radio wave interaction with plasmas.