基于瑞利-泰勒不稳定性的双球面弯晶成像测量技术研究

A novel dual-spherically crystal imaging measurement scheme, which breaks through the limits on the development of the Rayleigh-Taylor (RT) instability measurement, and realizes the measurement with the point backlight, monochromatic, high spatial resolution(<0.004mm) and large field of view(>1mm), is proposed. In this research, the dual-spherically crystal imaging technique is to be developed by integrating the advantages of KB microscope and spherically bent crystal spectroscopy imaging, and combining the concept of the equal resolution imaging，to break through the limits on the Bragg diffraction angle of incidence on the crystal surface, and to come true the high spatial resolution measurement of the RT instability. Using ray tracing code, optimization calculation is carried out on the relationship between spatial resolution and imaging efficiency, and realizes the optimum design method for the dual-spherically crystal imaging system. Based on the dual-spherically “mosaic” crystal imaging efficiency, it aims to conduct the research on the technologies related to the heat treatment and micro-fabrication with high degree of accuracy, and improves the integral diffraction coefficient of the spherically bent crystal. It is to set up dual-spherically crystal imaging system, to achieve the (1.5-20)keV monochromatic backlight imaging measurement under point backlight source , to overcome its key technology, and therefore it will lay the theory and technical foundation of the imaging measurement with high accuracy, large visual field, high spatial resolution and high reliability. As a result, in the research of inertial confinement fusion (ICF), astrophysics, medicine and biomolecule,et al, a completely new measurement method is developed with full independent intellectual property rights.

为了突破RT不稳定性测量瓶颈，实现点背光、单色性、大视场（>1mm）、高空间分辨力（<0.004mm）测量，开发一种双球面弯晶成像测量新技术。研究将KB显微成像方法移植球面弯晶，基于双球面弯晶成像方法，结合等分辨成像技术，打破布拉格角限制，实现高空间分辨力的RT不稳定性测量；研究一种权衡空间分辨力和成像效率互为制约关系技术，实现双球面弯晶成像系统的最佳化设计方法；基于球面弯晶，研究非完整“镶嵌”块晶体的晶体热处理和微纳米加工技术，实现大幅度提高球面弯晶积分衍射系数；建立基于布拉格角小于83度时双球面弯晶成像系统，以实现（1.5-20）keV单色背光成像诊断，攻克其关键技术，为实现高精度、大视场、高空间分辨力、高像质、高可靠性的单色X光背光双球面弯晶成像RT不稳定测量奠定理论与技术基础，为惯性约束聚变（ICF）、天体物理、医学、生物分子领域研究开拓一种完全自主知识产权的全新测量技术。

X光背光照相常用于高温稠密等离子体、惯性约束聚变（ICF）内爆过程等诊断。由于存在像散像差，球面弯晶背光成像难以取得令人满意的结果，因而本项目提出了双球面弯晶零像散像差成像技术方案。研究了双球面弯晶离轴非对称性的零像散差成像理论，结合等分辨成像技术，突破布拉格角应用范围限制，发展了高时空分辨力的准单色X射线背光成像技术。研究了各种因素对成像系统效率的影响，提出了提升成像效率的具体技术措施。基于双晶共心的消像散像差方法，研究探索了光学聚焦、自准直显微望远镜和切线圆定位方法，模拟仿真等技术措施，发展了一种用于双球面弯晶零像散像差的成像系统及其调节方法，解决了双晶共心和两个布拉格角精确匹配的技术难题，达到了成像系统高精度装调准直目的。研制完成了一种集点光源、小布拉格角（小于70度）、长工作距离、大视场和高空间分辨力于一身的准单色双球面弯晶X射线背光成像系统；开展了以双球面弯晶为分光元件的X射线能谱诊断和进行了激光等离子体辐射X射线能谱改造实验，分别得到了在光源=1mm条件下的能谱分辨力约为3577 X射线能谱和获得了准单色发散角好于2mrad的近平行X射线光束的结果。加深了对双球面弯晶成像消像散差机理了解，评估了双球面弯晶成像系统实现超高空间分辨力（近衍射极限）的可行性。利用新设计的双球面弯晶（一个凹晶和一个凸晶）成像系统，在神光II激光装置上搭建了双球面弯晶X射线背光成像实验平台。在实验中，进一步完善了双晶精确装调技术，从而积累和丰富了对瑞利-泰勒不稳定性增长测量的经验，为实现超高空间分辨力的高能X射线（>30keV）成像技术和后续设备研制提供了技术支撑，同时为建立全新的X射线成像技术奠定了理论与技术基础，对ICF诊断乃至可控热核聚变点火是否成功具有重大工程测量价值及理论意义和经济前景，也必将会在未来大型激光装置，以及医学、生物学和材料学等领域有很好的应用前景。