一种宽波段掠入射平场谱仪的概念设计

A Concept Design of Flat-Field Spectrograph for Wide Wavelength Range

等离子体辐射的谱线中包含着等离子体状态的大量信息。因此,探测等离子体状态参数的最有效手段之一就是等离子体辐射的谱线测量。现有的软X射线掠入射平场谱仪由于受到已有掠入射变间距凹面反射光栅的限制,在保持平焦场的情况下,可测量波段范围只有5～40nm。为了扩展掠入射XUV平场谱仪的测谱范围,首先编制了掠入射变间距凹面反射光栅的光路追踪程序。然后与文献[6]同样条件下的结果进行了数值比较,结果表明我们的程序计算结果与Harada等的结果符合的非常好,从而验证了所编制光路追踪程序的可信性。最后利用所编程序对不同掠入射条件下变间距凹面反射光栅的平焦场变化情况进行了详细的数值研究。通过计算和分析表明,在保持软X射线波段范围5～40nm为平场不变的情况下,在45～80nm的超紫外线波段范围内找到了一个满足平焦场条件的平场面直线方程为y=-2.50x＋661.11的平场面,从而利用一块掠入射凹面光栅就可以将掠入射平场谱仪的波长范围从5～40nm扩展到5～80nm。这个结果即从理论上论证了将传统的掠入射平场谱仪从软X射线波段扩展到超紫外线（XUV）波段的可行性,也为提高了掠入射平场凹面光栅的使用性提出了新的设计思路。

The radiation spectrum from the plasmas contains a large amount of information of plasmas.Thus,one of the most effective methods to detecting the plasma parameters is measure the plasma radiation spectrum.Until now,since the restriction of the Toshiba mechanically ruled aberration-corrected concave gratings,the measurable wavelength range of the incidence flat-field grazing spectrometer in the soft X-ray range are only from 5to 40 nm.In order to extend the wavelength rang of grazing incidence flat-field spectrometer,first,agrazing incidence concave reflection grating ray-trace code is written using optical path equation.Second,under the same conditions with reference 6,we compare our numerical results with Harada＇s results.The results show that our results agree very well with the results of Harada.The results of comparison show that our ray-trace code is believable.Finally,the variety of the flat-field curves are detailedly investigated using the ray-trace code with the different grazing incidence conditions.The results show that the measurable wavelength range of the incidence flat-field grazing spectrometer are extended to 5～80nm from the soft X-ray wavelength range of 5～40nm.This result theoretically demonstrates the possibility of expanded the traditional band flat-field grazing incidence spectrometer from soft X-ray band to the extreme ultraviolet（XUV）,and also bring a new design ideas for improving the use of grazing incidence flat field concave grating.