Laser light absorption by short wavelength ion turbulence

The absorption of laser light due to short wavelength ion fluctuations (lambdaapprox.10 electron Debye lengths) is considered. The effective collision frequencies and heated electron distributions are computed as a function of plasma density and compared with theory. A simple upper bound to the level of ion turbulence is given, and several sources for the turbulence are discussed briefly. Finally, the absorption due to this mechanism in an inhomogeneous, expanding plasma is calculated by putting the estimate into a fluid code including wave propagation and density profile steepening by laser light pressure. The results are related to some recent experiments with short-pulse-length Nd laser light