以实现X光驱动的惯性约束核聚变为首要目标，人们正在进行未来Z箍缩装置的概念设计，数值模拟是主要的设计手段。本文针对未来Z箍缩驱动源和负载动态耦合的数值模拟开展研究，取得了以下的主要成果。 针对以往人们采用的未来Z箍缩驱动源全电路模型所存在的问题，本文建立了该驱动源的“场路混合模型”，其中整体径向传输线（MRTL）采用三维电磁场模型，驱动源的其它部分采用电路模型，实现了该混合模型和负载零维模型动态耦合的数值模拟。利用文献中的小型MRTL装置实验结果，验证了该场路混合建模方法的正确性。基于MRTL三维电磁场频域数值模拟结果，提取了S参数，构建了MRTL的二端口等效电路网络，将驱动源的“场路混合模型”转化为基于S参数的电路模型，大大减少了数值模拟所需的计算时间。 为了真实地反映Z箍缩负载等离子体动态演变和能量转化的物理过程，本文采用Z箍缩负载辐射磁流体（RMHD）模型，研究了未来Z箍缩驱动源“场路混合模型”和负载RMHD模型的动态耦合方法。首先提出了一种基于重复迭代的耦合方法，它无需开发接口程序，但计算耗时。接着开发了驱动源仿真软件和RMHD负载仿真软件的接口程序，实现了未来Z箍缩驱动源和RMHD负载动态耦合的数值模拟。基于数值模拟结果，发现某些未来Z箍缩概念设计给出的负载参数并不是最优的，并进行了优化改进；分析了未来Z箍缩装置中能量传输与分配过程，发现相比于传统Z箍缩装置，未来Z箍缩装置的能量传输效率得到了大幅提高。 基于MRTL三维电磁场频域数值模拟，本文发现在高频段某些特定频率点上电磁波传输系数突然急剧下降，其原因是电磁波发生了角向谐振的驻波现象。进一步研究发现：最低谐振频率对应的波长大约等于MRTL外圆周上相邻脉冲大电流源之间的角向距离（即弧长）。借助微波领域的微带环形谐振腔的磁壁模型，从理论上解释了这个现象。基于小型MRTL实验，从实验上证实了该现象的存在。这个重要发现有助于改进未来Z箍缩驱动源的概念设计，即正确地选择MRTL外圆周上相邻脉冲大电流源之间的角向距离（即最小的角向谐振频率对应的波长），使其避开驱动电流主频率对应的波长。
Recently, many conceptual designs of future Z-pinch accelerators have been proposed for realizing X-ray inertial confinement fusion. Those conceptual designs were basically made based on the numerical simulation. In this paper, the dynamic coupling between the future Z-pinch generator and the load was investigated with the numerical simulation. The main work includes： Most of the previous studies on the future Z-pinch generator are based on the full circuit model which will cause non-ignorable error. To solve this problem, we developed a field-circuit hybrid model, the three-dimensional (3-D) electromagnetic model for the monolithic radial transmission line (MRTL) and the circuit model for the rest of the generator. The dynamic coupling between the field-circuit hybrid model of the generator and the zero-dimensional (0-D) model of the load was realized. In consideration of the numerical simulation with the field-circuit hybrid model being time-consuming, MRTL was equivalent to a two-port circuit network based on the scattering transfer parameters (S parameters) drawn from the 3-D electromagnetic simulation of MRTL. By this method, the field-circuit hybrid model of the generator was converted to the circuit model based on S parameters and the computation time was greatly reduced. In order to investigate the physical processes of Z-pinch plasma, 0-D model of Z-pinch load was replaced with the radiation-magneto-hydrodynamics (RMHD) model. The method for dynamically coupling the field-circuit hybrid model of the generator to the RMHD model of Z-pinch load was investigated. The first method based on the iteration was proposed. It avoided to develop an interface program between the generator and the load, but it took too much computation time. The second method was to develop an interface program between the software for the generator simulation and the software for load simulation. The dynamic coupling between the future Z-pinch generator and the RMHD load was realized. From the results of our numerical simulation, it was found that the parameters of the Z-pinch load given in some conceptual designs of future Z-pinch accelerators are not optimal. The parameters of the Z-pinch load were optimized based on our simulation. The energy transmission process in the accelerator was analyzed, and it was found that the future Z-pinch accelerator has a higher efficiency in energy transmission than the traditional Z-pinch accelerator. The transmission characteristic of the MRTL was investigated with 3-D electromagnetic simulation. It was found that the MRTL has several resonant frequencies in high frequency region. At those resonant frequencies, the standing waves form azimuthally in a narrow ring near the input of the MRTL, so the electromagnetic waves cannot be delivered to the load. It is important to notice that the wavelength of the lowest resonant frequency is close to the arc length between the neighboring input ports. The resonance in the MRTL at the resonant frequencies is similar to that in the microstrip ring resonator because the MRTL is similar in structure and close in resonant frequency to the microstrip ring resonator. The phenomenon of the resonant frequencies in the MRTL was confirmed in the experiment with a small MRTL. The discovery of the resonant frequencies in the MRTL is helpful for designing the MRTL reasonably. The MRTL should be designed to keep its lowest resonant frequency higher than its maximum operating frequency.
