Angular distribution of hot electrons incident on a laser-irradiated target

Angular distributions of bremsstrahlung emission are calculated for various energy and angular distributions of hot electrons incident on a laser-irradiated plastic target. These theoretical results are used to interpret experimental data of x-ray continuum emission from a C${\mathrm{O}}_2$-laser-produced plasma. It is shown that at low irradiance ($I_L\le 5\times {10}^{12}$ W/${\mathrm{cm}}^2$) the incident electrons are normal to the target surface but that at higher irradiance, the incident electrons' angular distribution (spatially integrated over the target surface) is semi-isotropic. The influence of the directional distribution of hot electrons on axial energy transport is also studied by comparing calculated continum x-ray spectra as well as energy-deposition profiles with experimental results.