Measurements of X-ray spectral opacity of dense plasma at ISKRA-5 laser facility

Powerful iodine ISKRA-5 laser facility was upgraded and now operates on the second harmonic. Experiments were performed to measure the x-ray spectral opacity of dense plasma of different materials. Sample of material under study was fabricated as a thin plate with the 0.1-0.15 $\mu$m thickness and was heated by the soft x-rays generated by irradiation of a thin film gold converter by one beam of the ISKRA-5 laser facility. Typical laser intensity on the converter was (1-5)$\cdot$10$^{13}$ W/cm$^{2}$ and laser pulse duration was 0.5-0.6 ns. The effective temperature of sample under experimental conditions didn't exceed 30-40 eV. The sample was tampered by $\sim$ 1 $\mu$m plastic layers on both sides to avoid its rarefaction during heating and to obtain a quasistationary layer of a dense plasma prepared to be probed by a backlighter. The backlighter was aluminum or dysprosium film irradiated by another beam of the ISKRA-5 laser facility with an intensity of 10$^{14}$-10$^{15}$ W/cm$^{2}$. Probe x-rays were registered by a Bragg spectrometer with spatial resolution. Comparison between experimental data and simulations is discussed