Quantum-kinetic theory of electron heating in plasmas by high-frequency electromagnetic waves

Abstract

The heating rate of electrons in laser-irradiated plasmas is derived from the quantum-mechanically extended Vlasov equation. The heating of electrons is shown to be due to (i) the electron velocity space diffusion by plasma waves, which are induced by the laser field (classical turbulent heating), (ii) the microscopic quantum mechanical interaction between each electron and the laser field in the electric field of the plasma waves (collisionless inverse bremsstrahlung), and (iii) collisional inverse bremsstrahlung in the static plasma field. A quasilinear equation for the changes of the electron distribution function by these three concomitant mechanisms is derived, and the heating rates of the electrons are calculated. It is shown that the collisionless inverse bremsstrahlung is dominant for hot plasmas in most experimental cases. The so-called anomalous heating is identified as being due to collisionless inverse bremsstrahlung, and is explicitly expressed in terms of the wavenumber of the plasma wave and the plasma parameters, when the turbulence is due to the ion acoustic instability and is stabilized by ion trapping.