Evidence of resonance absorption in laser-produced plasmas from the polarization and angular dependence of high-energy x-ray bremsstrahlung emission

Measurements are reported of the polarization and angular dependence of the amplitude and ’’temperature’’ of high-energy bremsstrahlung emission from planar copper targets irradiated with 25-psec neodymium laser pulses at 5±2×1014 W/cm2. A resonance in the emission is observed for p-polarized incident radiation at an angle of incidence of 25°. The results indicate the presence of plasma density scale lengths of about 1 μm and 17% absorption due to the resonance absorption mechanism.