激光等离子体X射线背光源诊断研究

Diagnosis of X-Ray Backlighter Based on Laser Plasma

为诊断激光驱动金属靶产生X射线背光源的性能，利用椭圆聚焦特性，研制了一种背光椭圆晶体谱仪。谱仪的色散分析元件为云母（002）晶体，椭圆弯晶的焦距为1350mm，离心率为0．9586。激光束以30°角斜入射背光薄靶，且与椭圆弯晶长轴方向垂直。背光椭圆弯晶谱仪的布拉格入射角为50°～67°，衍射探测角为100°～120°，探测的波长为0．14～0．16nm，采用X射线CCD相机接收信号。利用神光Ⅱ激光装置7#和8#激光器同时聚焦轰击10μm厚的Cu平面背光薄靶，CCD成功获取了Cu等离子体X射线的类氦和Ka谱线。经解谱发现谱线有明显基底，用最小二乘法差值去噪处理后，实测谱线分辨率（λ／△λ）大于700。

To study the characteristics of X-ray backlighter generated by laser irradiating a foil, a backlit elliptically bent crystal spectrometer is developed based on the ellipse focusing theory. The elliptical mica （002） crystal is employed with 1350 mm focal length, 0. 9586 eccentricity and 50°-67° Bragg angle. The laser is of 30° incident angle and perpendicular to long axis of elliptical mica. Diffraction detecting angle is 100°- 120° and the wavelength is 0.14-0.16 nm. X-ray CCD is taken as the signal detector. The experiment is carried out on SG Ⅱ where the 7 and 8 # lasers irradiate 10 μm Cu foil simultaneously. CCD obtains the X-ray spectral information of the similar helium and Ka spectra of Cu plasma X-ray. It is demonstrated by spectrum unfolding that spectral lines have obvious basement, and the spectral resolution is over 700 after difference denoising with the least square method.