2D spatially resolved spectroscopic diagnostics using a single convex crystal

Abstract

2D X-ray imaging spectroscopic diagnostics is an advanced plasma diagnostics tool, providing a way to determine the spatial dependence of plasma temperature and density (Te and ne) in hot plasmas. This can be accomplished with the usual spectroscopic diagnostics methods by taking advantage of the spatial information contained in the broad energy range spectra recorded by convex crystal spectrometers. The sensitivity of these instruments to the size of the X-ray source has long been noted, mostly as a factor leading to the reduction of the resolving power. Spectra can be spatially resolved by using a slit to create an image of the source in the direction perpendicular to the spectral dispersion. In the case of such spectra recorded by convex crystal spectrometers, it is often noted that the shape of the lines themselves, as recorded on a medium, resembles the shape of the plasma source as obtained, for example, with pinhole imaging. This provides some crude resolution perpendicular to the spectral line. We propose to use this effect for a new diagnostics technique that allows 2D spatially resolved spectroscopy of the X-ray source. Modeling the plasma emission spectrum by the PrismSPECT code allowed the identification of suitable spectral features to determine ne and Te. For an Al-Mg wire array z-pinch, the optically thin Mg lines can be used. We applied the principles of this method to get a temperature distribution map for a z-pinch from the shape of the Mg K-shell lines recorded by a convex KAP sprectrometer. The spatial resolution can be improved by deconvolving the plasma broadened line profiles from the lineshapes recorded by the convex crystal spectrometer. To obtain lineshapes with minimum instrumental broadening, a concave cylindrically bent KAP crystal spectrometer was designed.2D X-ray imaging spectroscopic diagnostics is an advanced plasma diagnostics tool, providing a way to determine the spatial dependence of plasma temperature and density (Te and ne) in hot plasmas. This can be accomplished with the usual spectroscopic diagnostics methods by taking advantage of the spatial information contained in the broad energy range spectra recorded by convex crystal spectrometers. The sensitivity of these instruments to the size of the X-ray source has long been noted, mostly as a factor leading to the reduction of the resolving power. Spectra can be spatially resolved by using a slit to create an image of the source in the direction perpendicular to the spectral dispersion. In the case of such spectra recorded by convex crystal spectrometers, it is often noted that the shape of the lines themselves, as recorded on a medium, resembles the shape of the plasma source as obtained, for example, with pinhole imaging. This provides some crude resolution perpendicular to the spectral line. We propose to use this effect for a new diagnostics technique that allows 2D spatially resolved spectroscopy of the X-ray source. Modeling the plasma emission spectrum by the PrismSPECT code allowed the identification of suitable spectral features to determine ne and Te. For an Al-Mg wire array z-pinch, the optically thin Mg lines can be used. We applied the principles of this method to get a temperature distribution map for a z-pinch from the shape of the Mg K-shell lines recorded by a convex KAP sprectrometer. The spatial resolution can be improved by deconvolving the plasma broadened line profiles from the lineshapes recorded by the convex crystal spectrometer. To obtain lineshapes with minimum instrumental broadening, a concave cylindrically bent KAP crystal spectrometer was designed.