Enhanced accuracy of x-ray spectra reconstruction from filtered diode array measurements by adding a time integrated spectrometer

Abstract

A new approach for the spectral reconstruction of time-dependent emission of soft x-ray sources based on the measurement of filtered x-ray diode array systems is suggested. Two reconstruction methods, based on this approach, are demonstrated using both simulated and measured data. The methods use the filtered x-ray diode measurement together with a co-aligned, time-integrated, spectrally resolved measurement, such as transmission grating spectroscopy. The additional experimental information allows for high accuracy spectral reconstruction, even for plasmas far from local thermodynamic equilibrium where the traditional reconstruction methods may miss some important source spectral features. For the demonstrated cases, the accuracy of the new reconstruction methods is better than 10% for the energy dependent flux and 1% of the total flux, which is higher than the accuracy of previous methods and better than the accuracy of the measurement itself.

A genetic algorithm approach to reconstructing spectral content from filtered x-ray diode array spectrometers

“…Other approaches suggest that more physical spectral reconstructions can be obtained when a priori spectral information via candidate spectra -provided either through modeling, experimental measurements, or with analytic physics models -is incorporated into the reconstruction routine 9,10 . The Levenberg-Marquardt method 4 , for example, is routinely employed to analyze inertial confinement fusion hohlraums 11 which models the x-ray emission as a linear combination of analytic bremsstrahlung, M-band (approximated as a gaussian bump), and Planckian (thermal) forms.…”