The splitter grating used in the Soft X-ray laser interferometer for plasma diagnosis

摘要

The short wavelength, high brightness and good spatial coherence of soft x-ray lasers make them ideal sources for the diagnostics of dense plasmas. As a widely used diagnosing tool in the research of laser-produced plasma, interferometry has many advantages in the accurate measurement of the plasma electron density because it directly gives refraction index mapping from the interference pattern processing. The electron density gradient and electron density of larger variety plasma will be probed by the soft X-ray diffraction grating Mach-Zehnder interferometer (DGI). At the wavelength 13.9nm which our DGI uses, we fabricate a laminar grating used as the splitter grating. Its groove density is 1000g/mm, groove depth is 13nm, duty cycle is 0.4±10%. The zero and first diffracted order beams have an equal metrical diffraction efficiency about 25 percent at 81.3 degrees, and the maximum of the product is 7.6 percent at 81.2 degrees. The results illustrate the laminar grating is suitable for being used as a new pattern splitter grating at the wavelength 13.9nm.