INTENSITY DEPENDENCE OF INVERSE BREMSSTRAHLUNG ABSORPTION IN AN INHOMOGENEOUS STANDING WAVE

The intensity dependence of inverse bremsstrahlung due to the oscillating velocity of electrons in a laser field can severely degrade collisional absorption efficiency. Previous work has concentrated on the classical and quantum expressions for the absorption rate. Total absorption requires evaluation of such expressions in the inhomogeneous field structure within the plasma, however. Both analytic and numerical calculations to determine the magnitude of the fractional reduction in absorption have been undertaken for the realistic case of an inhomogeneous standing wave. A simple physical model is derived and extrapolated to Airy-like field distributions. Numerical calculations employing fluid simulations with a heuristic intensity dependence were found to be in excellent agreement with an analytic model. © 1978 American Institute of Physics.