水靶激光等离子体光源11～20nm波段光谱实验

Experimental study of the spectrum at 11 ～20 nm of a laser-produced plasma source using water target

实验以水为靶材,Nd:YAG激光器为照射激光构成激光等离子体光源,产生软X射线极紫外辐射。利用McPHERSON247型掠入射软X射线真空紫外单色仪、AXUV100硅光电二极管,测量了11～20nm波段水靶激光等离子体光源的光谱。实验表明,在11～20nm波段水靶激光等离子体光源存在多条线谱,均由水中氧离子电子跃迁产生。所用单色仪光谱分辨率Δλ≤0.075nm,波长扫描间隔0.5nm。另外,采用在喷嘴处加热的办法,很好地解决了水进入真空系统后绝热膨胀与蒸发过程中温度骤降而结冰的问题,有效地抑制了喷射距离缩短,克服了等离子体对喷嘴腐蚀严重的问题。

A laser-produced plasma (LPP) source is built with water as target and a Nd:YAG laser as irradiate laser, the radiation of the LPP source at 11-20 nm is measured with an AXUV100 silicon photodiode combined with a McPHERSON model 247 grazing incidence monochromator, of which the monochromator resolution is Δλ&le0.075 nm, and the wavelength scanning interval is 0.5 nm. The experimental result demonstrates that the water target LPP source has EUV emission at 11-20 nm wavelength, which are all generated from electronic transitions in oxygen ions. In addition, to solve the erosion problem caused by the short distance between the laser-water action point and the nozzle, the distance is lengthened by heating the nozzle to reduce the effect caused by the evaporation and the adiabatic expansion.