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

根据实验结果、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射线激光泵浦源的潜力。快脉冲电源驱动的Z放电可以产生轴对称、高能量密度、大纵横比的等离子体。通过对预电离的良好控制，使快速内爆的z箍缩等离子体具有良好的再现性。与激光激发方案不同，放电泵浦利用压缩过程产生高能量密度等离子体。这样就可以控制等离子体在最终压缩阶段的状态，从而获得最佳的等离子体参数和结构，用于泵浦激光线。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的上升时间。最后对短波长工作的前景进行了展望，指出通过优化这些放电参数，可以实现软X射线波段的大能量输出。

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.