基于X射线激光脉冲短、单色性好、能量高而且相干程度高的优点,本文从理论上提出X射线激光干涉用于对晶体结构及缺陷的测量。 由于X射线激光波长量级为10-10m,因此可实现高精密测量。此外,本文给出了X射线激光测量晶体的装置、缺陷晶体的测量模型和晶体参量的测量模型。

Using an X-ray free electron laser (XFEL) at 960 eV to photo-ionize the 1s electron in neutral neon followed by lasing on the 2p-1s transition in singly-ionized neon, an inner-shell X-ray laser was demonstrated at 849 eV in singly-ionized neon gas several years ago. It took decades to demonstrate this scheme, because it required a very strong X-ray source that could photo-ionize the 1s (K shell) electron in neon on a timescale comparable to the intrinsic Auger lifetime in neon of 2 fs. In this paper, we model the neon inner shell X-ray laser under similar conditions to those used in the XFEL experiments at the SLAC Linac Coherent Light Source (LCLS), and show how we can improve the efficiency of the neon laser and reduce the drive requirements by tuning the XFEL to the 1s-3p transition in neutral neon in order to create gain on the 2p-1s line in neutral neon. We also show how the XFEL could be used to photo-ionize L-shell electrons to drive gain on n=3-2 transitions in singlyionized Ar and Cu plasmas. These bright, coherent, and monochromatic X-ray lasers may prove very useful for doing high-resolution spectroscopy and for studying non-linear process in the X-ray regime.

To probe the electron density distribution of the plasma,double-frequency grating shearing interferometry based on the soft X-ray laser technology is developed.The 13.9 nm Ni-like Ag soft X-ray laser is used as a probe to make attempt on the diagnosis of laser produced plasma from a planar gold wafer target.Clear interference fringes image is achieved,which fully demonstrates the practicability of this technology.However,there are some problems such as the unclear target surface in the image.Analysis indicates the main reasons of these problems and a reasonable solution is proposed to improve this technology.

针对高温稠密激光等离子体临界密度附近电子密度的诊断需求,发展了基于软X射线激光的软X射线双频光栅干涉诊断技术.利用波长13.9 nm的类镍银软X射线激光作为探针,掠入射式的双频光栅作为分光干涉元件,对激光辐照金平面靶产生的等离子体进行诊断尝试.实验获得了清晰的干涉条纹图像,充分表明该技术的实用性.但结果中存在靶面不清晰等问题,为此,提出了初步的解决方案.

It is important to diagnose electron density of a plasma irradiated by lasers for inertial confinement fusion, in high energy density physics and related fields, especially for measuring high-Z plasma near the interface. Use of soft X-ray laser as a probe is an important method in diagnosis of plasma electron density distribution. However, it is difficult to carry out the research in high-Z laser plasma, because of the problem of excessive plasma spontaneous radiation. In view of the characteristics of soft X-ray laser, several specific experimental techniques have been developed. By using these techniques, which can greatly suppress effects of spontaneous radiation, diagnosis of high-Z plasma with soft X-ray laser probe method becomes possible. As a typical example, an experiment of diagnosing gold plasma is performed and clear images are obtained, indicating that the techniques are effective and feasible.

The diagnoses of laser-produced plasma electron density have important significance for inertial confinement fusion, plasma physics, high energy density physics and other relevant fields, especially for measuring electron density distribution information of medium and high-Z material plasma near the critical density surface. With 13.9 nm Ni-like Ag X-ray laser serving as a probe, using double frequency grating shearing interference technique, the electron density distribution of plasma produced by laser irradiating a gold planar target is measured. Clear interference fringe image is obtained. Preliminary deduction of the fringe shows that the maximum density measured is about 1.4 times the critical density. It is found that there are some discrepancies between experimental results and simulation results, which provides a useful reference to the further optimization of the simulation program. The experimental results fully demonstrate that the soft X-ray double frequency grating shearing interference technique is practical to diagnose near-critical-density plasma of medium and high-Z materials, which will have a good application value.

为了研究类镍氪32.8 nm激光输出所需的等离子体状态，利用Cowan程序计算了类镍氪32.8 nm激光系统的有关原子参数。根据能级参数，建立并求解了准稳态近似下的有关能级速率方程，计算获得了激光上、下能级的相对粒子数密度和相对增益系数随电子温度和电子密度的变化规律，并分析了3d94p、3d94d和3d94f组态的能级对激光产生的影响。通过理论计算得到实现类镍氪32.8 nm激光输出所需的最佳等离子体状态。最佳电子温度约为75 eV，最佳电子密度约为1018 cm-3。计算结果为未来开展毛细管放电抽运类镍氪32.8 nm激光实验提供了理论依据。

充分利用全固态激光器结构紧凑的优点，设计了一套紧凑型直腔式457 nm蓝光激光器系统。在设计过程中，针对Nd:YVO4激光晶体的自身性质及其产生914 nm激光的相关光学特性，着重对该激光系统的激光阈值进行分析，对温控系统及谐振腔参数进行优化。最终实现了Nd:YVO4激光晶体914 nm波长激光运转，并在此基础上利用BIBO晶体进行腔内倍频获得457 nm激光输出。入射抽运光功率为24.2 W时，最高输出功率为1.56 W，光光转换效率为6.45%，功率稳定度低于2.98%，M2因子为1.3。

如何人为地诱发同核异能态辐射，从而利用储存在其中的巨大能量，是个备受关注的交叉学科课题。利用原子物理过程进行触发是目前较为可行的方案，原子物理参数将在里面起到关键作用。介绍了一套高效率的原子数据库，目前该数据库可对原子序数小于９６的元素所有电离度离子的能级结构信息进行快速扫描，从而筛选出一些可能通过原子过程触发的同核异能态体系。通过在197Au元素电子跃迁诱导核激发过程和178Hf元素电子俘获诱导核激发过程中的应用,展示了该数据库对寻找合适同核异能态体系的作用。isomer triggering via nuclear excitation

为了提高毛细管放电类氖氩46.9 nm软X射线激光的强度，研究了主脉冲电流波形对等离子体Z箍缩过程、激光的产生时间及激光强度的影响。通过改变主开关导通电感，实现了对主脉冲电流上升沿的改变。随着电流上升沿的增加，激光尖峰幅值减小，激光产生时间增加。实验进一步研究了平均电流变化率对激光强度的影响:在毛细管内径3 mm、管内初始气压30 Pa的情况下，产生46.9 nm激光的最佳平均电流变化率约为7.0×1011 A/s。