Fresnel absorption, resonance absorption, and x rays in laser-produced plasmas

Assuming Fresnel absorption for s-polarized light and resonance absorption for p-polarized light provides agreement with the significant features of subpicosecond high-intensity KrF laser-produced plasma experiments. These features include the s- and p-light angular dependence and magnitude of the reflectance. Dramatic differences exist in the threshold for emission of x-ray photons above 0.5 keV, the x-ray emission intensity, and the efficiency for x-ray production by absorbed p and s light. It is shown that resonant p-light absorption occurs at the laser critical density and that the s-light absorption at a higher electron density causes more efficient x-ray production by p light than by s light.