Laser-assisted inverse bremsstrahlung in a weakly ionised plasma

Abstract

Effective electron-ion and electron-atom cross sections and energy changes in a slightly ionised gas when a laser field is present are derived. The numerical analysis is restricted to: (i) weak laser fields; (ii) mean electron kinetic energy greater than the laser photon energy; and (iii) an average electron-atom collision frequency much smaller than the frequency of the assisting field. The electron-ion cross section exhibits a sharp decreasing behaviour as a function of the laser intensity, and significant changes against the laser frequency. The electron-atom cross section shows a more smooth behaviour against the laser intensity and frequency. The energy changes are very rapidly decreasing functions of the laser frequency and are, generally, non-linear rising functions of the intensity.