用修正双晶技术诊断激光等离子体X射线极化度

Diagnosis of X-ray polarized spectrum of laser-produced plasma by modified double-crystal method

研制了激光等离子体极化光谱仪,用于诊断波长为0.2～20nm的激光等离子体X射线的极化度并推断等离子体内部的各向异性状态。设计的谱仪在电子束垂直入射面内正交布置的色散元件均为PET晶体,两通道均用成像板接收光谱信号,其有效面积为30mm×80mm,从光源经晶体到成像板的光程分别为980mm和310mm。在中国工程物理研究院激光聚变研究中心20J激光器上进行固体靶实验,获得了Al离子类氦谱线,经过对类氦共振线和互组合线校正,推算出两谱线的极化度分别为0.123 3和0.148 1。结果表明,激光等离子体内部存在弱各向异性,该谱仪适用于激光等离子体极化光谱的诊断。

A polarized spectroscopy was designed and manufactured based on the laser-produced plasma experiments to diagnose the X-ray polarization of a laser-produced plasma in 0.2-20 nm.The experiment was performed at the 20 J laser facility in Research Center of Laser Fusion,China Academy of Engineering Physics（CAEP）.In the experiment,Poly Ethylene Terephthalate（PET） crystals were used as dispersive elements in the two orthogonal directions and the imaging plates with the effective area of 30 mm×80 mm were taken as detectors.The optical paths of the X-ray beam were about 980 mm and 310 mm from the source to the detectors via the PET crystals,respectively.The X-ray spectrum emitted from the aluminum plasmas was recorded by the image plates.It shows that the polarization of the two Al Ⅻ spectra are about 0.123 3 and 0.148 1 after correcting helium resonance and combination spectrum.The experimental results demonstrate that there is anisotropic phenomenon in the laser-produced plasma,and the proposed method is effective to diagnosis of the polarized spectrum of high-temperature plasma.