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-μm wavelengths, and (1–3)×${10}^{14}$-W/${\mathrm{cm}}^2$ 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 μm along the laser axis. The electronic density and temperature are deduced from Stark broadening and intensity ratios of ${\mathrm{Al}}^{11+}$ and ${\mathrm{Al}}^{12+}$ 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.