Wavelength Scaling of Soft X-ray Lasers Pumped by Fast Capillary Discharges

基于实验结果、数值模拟和非均匀激光介质中受激辐射放大过程的解析模型，讨论了快速毛细管放电等离子体作为软x射线激光抽运源的潜力。由快速脉冲发生器驱动的z型放电可以产生大纵横比的轴对称高能量密度等离子体。在控制良好的预电离条件下，可使快速内爆的z夹缩等离子体具有良好的再现性。与激光激发方案相比，放电泵浦采用压缩过程制备高能量密度等离子体。这样就可以控制最终压缩阶段的等离子体，从而使等离子体的参数和结构达到最优，从而泵送激光线。在该方案中，有许多控制参数，如初始气体压力、直径、峰值电流和驱动电流上升时间。讨论了在较短波长区域运行的前景，并得出结论，通过优化这些放电参数，可以在软x射线区域获得较大的能量输出。

Based on experimental results, numerical simulations, and an analytical model for amplification process of stimulated radiation in inhomogeneous laser mediums, the potentiality of fast capillary discharge plasma as a pumping source of soft X-ray laser is discussed. Z-discharges driven by fast pulse power generator can make axi-symmetric and high energy density plasmas with large aspect ratio. With well controlled pre-ionization, it makes the rapidly imploding z-pinch plasma with good reproducibility. In contrast to laser excited scheme, the discharge pumping uses compression process for making the high energy density plasma. Thus the plasma at final compression phase can be controlled so as to make optimum parameter and structure of plasma for pumping the laser line. In this scheme, there are a lot of control parameters such as the initial gas pressure, the diameter, the peak current and the rise time of drive current. A prospect for the operation at shorter wavelength region was discussed and we could conclude that with optimization of those discharge parameters, we can expect large energy output at soft X-ray region.