High-Resolution X-Ray Spectroscopy of a 80 fs Laser-Produced Al Plasma

Aluminum targets irradiated with intense (I ~ 1017W/cm2) 80 fs laser pulses are shown to emit strong K? lines in the kV spectral region. The analysis of the spectra indicates that suprathermal electrons play an important role in the laser energy deposition and transport. Hydrodynamic simulations taking into account hot electron transport are in quantitative agreement with the measurements. Based on these simulations, the duration of the suprathermal X-ray emission is shown to be comparable to the incident optical pulse.