X-ray spectroscopic studies of the electronic density and temperature profiles in the transport region of 0.53- and 0.26-μm laser plasmas

We present the first space-resolved experimental determination of electronic density and temperature profiles in the transport region for plane target irradiation with 400--600-ps pulses at 0.53- and 0.26-{μ}m wavelengths, and (1--3)×{}10¹⁴-W/cm² laser intensity. The experimental technique is x-ray spot spectroscopy on thin Al microdots deposited on a carbon substrate. A knife-edge imaging technique ensures a spatial resolution of 3 {μ}m along the laser axis. The electronic density and temperature are deduced from Stark broadening and intensity ratios of Al¹¹⁺ and Al¹²⁺ n=4 resonance lines, respectively. The experimental profiles are well reproduced by one-dimensional spherical simulations including nonlocalized thermal flux inhibition or very low inhibition.