Reconstruction of Z-pinch emission spectra in the wavelength range of less than 10 Å using a crystal X-ray spectrograph

Abstract

This work is devoted to the reconstruction of Z-pinch plasma emission spectra in the wavelength range of less than 10 Å recorded by using a crystal x-ray spectrograph at the Angara 5-1 mega-ampere facility. The spectrograph JA-1 used in experiments has a cylindrical mica crystal with dimensions of 50 × 40 mm2 and radius of curvature of 100 mm. Registration of spectra is performed on the photographic film UF-4 with dimensions of 30 × 10 mm2. To reconstruct the spectra, the previously developed method based on iterative approximation of a true spectrum shape while minimizing a residual between experimental and calculated spectrograms is used. The calculated spectrogram was obtained taking into account the instrumental function of the spectrograph. To define the instrumental function a virtual Monte-Carlo model in the Geant4 toolkit has been developed. This model takes into account the interaction of radiation with the mica crystal using dynamical theory of diffraction. A true spectrum of Z-pinch plasma radiation is reconstructed for a 16 mm high load made of two nested cylindrical wire liners. External liner with a diameter of 12 mm has 40 Al wires with a diameter of 18 μm. The internal liner with a diameter of 5 mm has 4 W wires with a diameter of 6 μm. The W wires have a sputtered layer of Re that is 0.5 μm thick.