A variable-sagittal-radius elliptical x-ray crystal spectrometer for time-resolved diagnostics of laser-generated plasmas*

Time-resolved x-ray spectroscopy of small-source-size laser-generated plasmas is commonly performed using Hall’s conical x-ray spectrometer [1]. A variable-sagittal-radius conical shape of the spectrometer crystal, which improves imaging properties of the spectrometer was recently proposed [2]. In this presentation we introduce and describe a variable-sagittal-radius elliptical crystal shape as an alternative option for the time-resolved x-ray spectroscopy. The advantages of the new approach include extended total photon energy range for a fixed length of the crystal and increased spectrometer sensitivity at higher energies. In addition, the spectrometer’s detector can be better shielded from divergent background radiation by placing a narrow aperture at the location of crossing of x-rays reflected from the elliptical surface of the crystal.  These properties are expected to yield superior time-resolved spectroscopy of x-ray continuum in the photon energy range 20-30 keV [3]. Such spectroscopy is expected to play a vital role for time-resolved characterization of electron temperature in high-neutron-yield inertial confinement fusion experiments at the National Ignition Facility.  

 

[1] T.A. Hall, J. Phys. E: Sci. Instrum. 17, 110 (1984) 

[2] M. Bitter et al., Rev. Sci. Instrum. 87, 11E333 (2016) 

[3] M.J. MacDonald et al., J. Instrum. 14, P12009 (2019) Acknowledgments: