Research of elliptical curved crystal spectrometer for measuring laser-produced plasma x-ray

Abstract

A new space and time resolved focusing elliptical curved crystal spectrometer has been developed and applied to diagnose X-ray of laser-produced plasma in 0. 2~2 nm region. According to the theory of Bragg diffraction, four kinds of crystal including LiF, PET, KAP, and MiCa were choosed as dispersive elements.The distance of crystal lattice varies from 0.4 to 2.6 nm. Bragg angle is in the range of 30°~67.5°, the spectral detection angle is in 55.4°~134°. The dispersive crystal sizes are 120×8×0.2mm.The characteristic of optical system is an elliptical geometry.The X-ray source is located at the front focal point.The X-rays diffracted by the elliptically curved crystal are focused at the rear focal point where a width-adjustable exit slit is positioned.The Curved crystal spectrometer mainly consists of dispersive elements, vacuum configuration, aligning device, spectral detectors and three dimensional (3D) micro-adjustment devices. The spectrographic experiment was carried out on the XG-2 laser facility.The PET and KAP crystals are adopted as the dispersive elements,which measure X-ray in the 0.44~0.81 and 1.33~2.46nm region. Emission spectrum of Al plasmas and Ti plasmas have been successfully recorded by using X-ray CCD camera. It is demonstrated experimentally that the measured wavelength is accorded with the theoretical value. At the same time, experimental result shows that spectral resolution of PET and KAP crystals is 956 and 1123.