An examination of classical coupling of laser light to thin, dense plasma layers

Classical coupling, i. e. net absorption by inverse bremsstrahlung, of laser radiation in thin layers of dense (n >> n
_c
) plasmas is described by Eqs. (19) and (26) according to a wave description of the radiation field and a simple hydrodynamic model of the plasma and by Eqs. (29) and (47) according to a photon transport model. Though it appears that neither of these descriptions can be explored further without computer assistance, their implications seem to be quite discrepant. Equation (28) implies that the Maxwell-hydrodynamic model leads to high reflectivity of thin, dense plasma layers. Equation (47), on the other hand, implies - because of the smallness of Γ ~ υ
_ei
/w ~10
^-3
- 10
^-2
- that any plasma layer is extremely absorptive in the density region for which n ~ n
_c
. Though this discrepancy is, so far, based only upon qualitative arguments, it nevertheless appears real.