利用多孔结构原理,研制了厚度为100 μm、孔隙率为70%的纳米多孔铜靶,密度比为固体铜的30%。实验在中国工程物理研究院“星光Ⅲ”激光装置飞秒激光束上进行,激光功率密度大于1.6×1018 W/cm2,脉宽为30 fs。利用16 bit单光子CCD获取了X射线能谱,测得铜Kα线光子产额为2.9×108 photon·sr-1·s-1,转换效率为0.008 38%。与压制加工的平面Cu靶相比,多孔结构靶的X射线产额约为平面靶的1.8倍,表明纳米多孔结构能够有效增强飞秒激光能量吸收,提高超热电子和X射线转化效率。

Based on a porous structure principle, the nano-foam Cu targets were developed with a thickness of 100 μm,a porosity of 70%, the density ratio of 30% solids of Cu. Experiments had been carried out on XG-Ⅲ laser facility in Laser Fusion Research Center, China Academy of Engineering Physics. The minimum laser intensity was more than 1.6×1018 W/cm2 with a duration of 30 fs. A single-photon-counting X-ray CCD was used to measure Kα spectrum of the X-ray source. The X-ray yield was counted to achieve Kα peak photons of 2.9×108 photos·sr-1·s-1 from femtosecond irradiated nano-foam Cu. The Kα X-ray conversion efficiency (CE) reaches the maximum value 0.008 38%. Compared to the pressed Cu foil target, the average X-ray yields of nano-foam structures increased by 1.8 times. The results show that nano-foam structure can effectively enhance the energy absorbability of femtosecond laser and improve the conversion efficiency from ultra intense laser to hot electron and X-ray.研究项目(KJ120710); 国家智能制造服务国际科技合作基地项目(1456043); 重庆市发展信息管理工程技术研究中心开放基金项目(gczxkf201503)