594 / 2019-04-25 12:00:02

Design and performance of single-order multilayer diffraction gratings

Mutilayer gratings,X-ray,Spectroscopy

全体主题 > Laser and Particle Beam Fusion

The single-order diffraction grating has diffraction characteristics of gennerating pure soft x ray spectra in the first diffraction order, free from interference with higher diffraction orders,which makes it play an important role in laser plasma diagnostics. However, in the tender x ray range(2kev~5kev) , the traditional single-order diffraction grating can not achieve the ideal diffraction efficiency.
The radiation in tender x ray range can be dispersive by incident on the total reflection device at a small grazing incident angle,or we might use a multilayer as a monochromator, which could get rid of the grazing incidence limitation and utilize a larger angle of incidence. Yet due to the absorption of x-rays, the number of period of the multilayer is also greatly limited. This results in a poor monochromaticity of the beam after diffraction by the multilayer, and it still has a band of a certain wavelength range.
This work introduce the structure of periodic gratings into the multilayer. That is, a multilayer is deposited on a grooved metal substrate, or a series of concave and convex groove are etched on the multilayer to form a single-order multilayer diffraction grating. Combining the high resolution of the grating with the extreme reflectivity of the periodic multilayer, the multilayer diffrraction grating has new diffraction characteristics,which makes diffraction light with high intensity and excellent monochromaticity when incident at large angles. It is expected to provide (2kev~5kev) high resolution X-ray spectra of black cavity radiation for ICF.