皮秒激光驱动微丝靶产生的超热电子能谱实验研究  

Experimental Study on Ultra-thermal Electron Spectrum Generated by Picosecond Laser-driven Microwire Targets

作　　者：罗笔瀚 王洪建[1,2] 罗登成 冯永祯 LUO Bihan;WANG Hongjian;LUO Dengcheng;FENG Yongzhen(Smart Manufacturing Institute of Robot and Laser,Chongqing Technology and Business University,Chongqing 400067,China;Chongqing Key Laboratory of Manufacturing Equipment Mechanism Design and Control,Chongqing Technology and Business University,Chongqing 400067,China)

机构地区：[1]重庆工商大学机器人与激光智能制造研究所,重庆400067 [2]重庆工商大学制造装备机构设计与控制重庆市重点实验室,重庆400067

出　　处：《重庆工商大学学报（自然科学版）》2024年第5期80-86,共7页Journal of Chongqing Technology and Business University:Natural Science Edition

基　　金：国家自然科学基金委员会-中国工程物理研究院联合基金项目(U2030120);重庆工商大学研究生科研创新项目(YJSCXX2022-112-56)。

摘　　要：目的 针对激光辐照平面靶中超热电子束流发散角过大以及产生的X光源亮度不足的问题,提出采用高功率皮秒激光辐照微丝靶,研究电子再循环效应对超热电子束流和X光源特性的影响。方法 实验在“星光-Ⅲ”装置皮秒束激光器上进行,分别采用直径10μm的钼和金丝靶作为X射线背光源。利用针孔相机在激光反射方向测量X光焦斑,靶前法线方向布置电子磁谱仪测量逃逸出靶的超热电子能谱。结果 获得的X光焦斑的纵向尺寸最小值达到10μm,与丝靶直径相当。超热电子能谱结果显示自持独立钼丝和金丝中最高温度分别为863 keV和816keV,比对应的带CH衬底丝靶中的超热电子温度和数目均有显著提升。结论 说明移除支撑丝靶的低密度衬底是增强电子再循环效应的有效途径,通过这种方式能够提高超热电子束流的强度和集中度,增强轫致辐射强度,从而获得微焦点和高亮度的X射线源。Objective In response to the problem of excessive divergence angle of the ultra-thermal electron beam and insufficient brightness of the generated X-ray source in laser-irradiated planar targets,a high-power picosecond laser was proposed to irradiate the microwire targets and the effects of electron recirculation on the characteristics of ultra-thermal electron beam and X-ray source were studied.Methods The experiment was carried out on the XGIII laser device.The molybdenum with a diameter of 10μm and gold microwire targets were used as X-ray sources.A pinhole camera was used to measure the X-ray focal spot in the direction of laser reflection,and an electron magnetic spectrometer was arranged in the normal direction of the target to measure the ultra-thermal electron energy spectrum of the escaped hot electron from the target.Results The minimum size of the X-ray focal spot obtained by the pinhole camera reached 10μm,which was equivalent to the diameter of the wire target.The ultra-thermal electron energy spectrum results showed that the maximum temperatures in the self-sustaining independent molybdenum wire and gold wire were 863 keV and 816 keV,respectively,which were higher compared with the corresponding temperatures and quantities of ultra-thermal electrons in wire targets with CH substrates.Conclusion The experimental results show that removing the low-density substrate of the support wire target is an effective way to accelerate the electron recirculate effect.In this way,the intensity and concentration of the ultra-thermal electron beam can be improved,which enhances the X-ray bremsstrahlung radiant intensity,thus obtaining micro-focus and high-brightness X-ray sources.

关 键 词：皮秒激光 超热电子能谱 微丝靶 X光源 电子加速机制 

分 类 号：O358[理学—流体力学]