NUMERICAL-STUDIES OF THE ANOMALOUS SKIN EFFECT

Laser energy absorption and transmission by the anomalous skin effect has been studied numerically in hot plasmas, assuming a step-density profile and normal incidence. Our calculations are compared both to the normal skin effect and to that of Weibel [Phys. Fluids 10, 741 (1967)], who neglected the variation of the collision frequency with velocity. We find that the penetration of the field is considerably enhanced compared to that of Weibel, which is already far above that of the normal skin effect. This enhanced penetration means that fields of amplitudes 10(-3)-10(-2) of the incident amplitude exist at several normal skin depths beyond what would be expected from normal skin-effect calculations. Only in very hot (T(e) > 1 keV) and low-Z plasma does this absorption mechanism dominate, and it is then at most several percent. Field transmission through a thin target (about ten skin depths) is far higher than predicted on the basis of the normal skin effect: this could provide a possible means of observing the effect.