The target configuration. The ratio of the HXR signal from the two targets depends on the transport of the fast electrons in addition to the intrinsic dependence on the nuclear charge.
Measured temporal shape of the laser pulse and the HXR emission. Fast electrons are produced at the end of the laser pulse.
X-ray yield from thick Cu and CH targets (in units of the total electron energy) as a function of the fast-electron energy (from NIST tables, Ref. 18).
X-ray signals calculated for the targets of Fig. 1 (in units of the total fast-electron energy) as a function of the fast-electron temperature . The electrons were assumed to initially have a Maxwellian distribution of energies and to move radially inward (with no scattering). The x-ray spectra were multiplied by the sensitivity curve of the x-ray detector HXR2.
Calculated and measured ratio of the x-ray signals from the two targets of Fig. 1. The curve is calculated by a model assuming radial motion of the electrons. The points marked as MC are calculated by a Monte Carlo code; the higher point corresponds to no initial divergence of the electrons, while the lower point corresponds to a divergence of . The remaining points correspond to experimental results. The discrepancy with respect to the model is the result of excluding scattering and initial divergence in the model.
Measured (circles) and MC simulated (lines) signals of the three HXR detector channels (HXR2, HXR3, and HXR4) for Cu and CH targets. The simulation results for the Cu target are for two angular divergences of the fast electrons: (solid line) and (dashed line). The results for the CH target are independent of this divergence. The dashed line for the CH target is the result of the MC code corrected for the recycling of fast electrons. The MC points were connected by straight lines for clarity.
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