Vertical dispersion Johann x-ray spectrometer with asymmetrically cut crystal

Theoretical design of a new type of the bent crystal spectrometer based on a combination of the vertical dispersion principle with diffraction of x rays from the asymmetrically cut crystal is reported. The novel instrument produces simultaneously two sets of mirror-symmetric spectra, and provides large dispersion, high spectral and 1D spatial resolution with a variable magnification. The analytic formulas describing the function of the spectrometer are complemented by its detailed quantitative analysis based on the ray tracing procedure. The method for reconstruction of the recorded spectra is described, the parameters influencing the precision of the wavelength determination are discussed. The comparison of the main predicted and experimentally observed characteristics verifies the developed theory and demonstrates the spectrometer performance. The novel instrument is particularly suitable for precise measurements of profiles and positions of the narrow-band spectral features observed in the emission of laser-generated plasmas.