Resonance absorption in non-planar plasmas

The authors describe a numerical routine for the calculation of the absorption coefficient due to resonance absorption for plasmas with non-planar isodensity surfaces. The method used relies on the fact that in the linear approximation for resonance absorption, in plane-parallel plasma, the absorption coefficient depends exclusively upon the distance from the turning point to the critical surface, d t . For more complex geometries, the region between the turning point and the critical surface can still be assumed to be plane-parallel, in which case the absorption coefficient remains a sole function of d t . The determination of d t is accomplished using a ray tracing routine. The calculations and assumptions are valid within the limits of the WKB approximation. The method is illustrated by investigating the absorption and reflection of laser light by plasmas with a rippled critical surface.