A multi-cone x-ray imaging Bragg crystal spectrometer.

In a recent article, \textit{see }Rev. Sci. Instrum. \textbf{87}, 11E333 (2016), we described a new x-ray imaging Bragg crystal spectrometer, which -- in combination with a streak camera or a gated strip detector -- can be used for time-resolved measurements of x-ray line spectra at the National Ignition Facility (NIF) and other high power laser facilities. The main advantage of this instrument is that it produces perfect images of a point source for each wavelength in a selectable spectral range and that the detector plane can be inclined by an arbitrary angle with respect to the crystal surface. These unique imaging properties are obtained by bending the x-ray diffracting crystal into a certain shape, which is generated by arranging multiple cones with different aperture angles on a common nodal line. In this paper, we present results from optical tests of these multi-cone structures and numerical results on the deteriorations of the spectral and spatial resolutions that may be caused by potential misalignments of the source, crystal, and detector.