节点文献
S波段长脉冲相对论速调管放大器的理论与实验研究
【作者】 黄华；
【作者基本信息】 中国工程物理研究院 ， 无线电物理， 2006， 博士
【摘要】 相对论速调管放大器(Relativistic Klystron Amplifier)是一种高功率、高效率的微波器件。论文针对S波段长脉冲强流RKA进行了深入的理论分析，并开展了相应的实验研究，取得了与理论相符的实验结果。 论文理论分析分为三个方面： 1．采用三维模型，分析了RKA中强流相对论电子束(Intense Relativistic Electron Beams)与谐振腔间隙中的角向均匀和非均匀模式相互作用的动力学过程，分析结果证实，角向非均匀模式与电子束相互作用后会造成电子束的发散，为此提出了采用腔体较长的高阶模输入腔和输出腔，设计和调试出了场强角向分布比较均匀的输入腔和输出腔，减轻了电子束的发散问题，保证了强流调制长脉冲电子束的长距离稳定传输，在S波段RKA谐振腔的设计和微波调试实验中得到应用。 2．采用电磁场的等效原理，并利用格林函数积分法严格求解了大耦合孔同轴输出腔的本征频率、有载品质因数和特性阻抗等高频参数，建立了完整的三维解析表达式，为微波提取腔的计算机辅助计算和设计建立了解析分析模型和详细的计算公式，在S波段RKA输出腔的计算中得到应用。 3．分析了长脉冲IREB经过强电场作用间隙形成电子反射及自激振荡的物理过程，为此对谐振腔的参数设计提出了“参差模式”的设置方案，优化分析和模拟了三轴输出腔，减少了反射电子，抑制了自激振荡的形成，同时微波提取效率达到35％，比同轴输出腔提高了9个百分点。 根据理论分析结果，设计了S波段RKA，并采用PIC程序进行了数值模拟，确定了谐振腔的基本电参数和几何尺寸，给出了束流群聚的最佳位置、RKA运行的最佳参数与性能，以此进行了相应的高功率微波器件实验。 RKA的实验研究包括高频系统(包括输入腔、输出腔和辐射喇叭)的工程设计和实验调试，以及束流调制与微波提取的实验研究。在高频系统实验研究中，调试出了谐振频率、有载品质因数和场强角向分布等参数符合设计要求的输入腔和输出腔，减小了不均匀模式对电子束发散的影响。在RKA的微波实验中，通过优化调试输入腔、中间腔和输出腔参数，解决了长脉冲IREB的长距离稳定传输和群聚问题，减缓了RKA自激振荡的建立，减轻了强流调制电子束和输出微波的脉冲缩短问题。在螺旋线型强流脉冲加速器(电子束参数为550kV、4kA、210ns)的驱动下，输出微波功率580MW、频率2.85GHz、脉宽140ns，效率26％，增益34dB，与理论分析和模拟结果相吻合。
【Abstract】 Relativistic Klystron Amplifier (RKA) is one kind of microwave devices with high output microwave power and high efficiency. S-band long pulse intense current RKA are theoretical investigated deeply, and the corresponding conclusions are used to design and guide the RKA experiments. The experimental results are consistent with the theoretical results.The theoretical studies are divided into three parts:1. The dynamics of interaction between Intense Relativistic Electron Beams (IREB) and symmetric mode and asymmetric modes of cavity in RKA is analyzed three dimensionally. The interaction between IREB and asymmetric mode, which leads to the collapse of IREB, is obtained. The input cavity and the output cavity, which work in higher mode with long dimension, are proposed to decrease such influence. The collapse of IREB is controlled and IREB can drift longer. The results of theoretical studies are used in the design and adjustment of cavities in s-band RKA.2. The coaxial output-cavity with large coupling holes is theoretical analyzed based on equivalent principle of field and integral method of Green functions. The resonant frequency and loaded Q value and characteristic impedance of the cavity are solved by three dimensions. The results ared used in the calculation of cavities.3. Space-charge-limited current and energy distribution of annular IREB in coaxial drifting pipe and in cylinder drifting pipe are analyzed. The physical process of reflected electron and self-excited oscillation is described when the long pulse IREB drifts through the gaps of cavities with high electrical field. The structure of uneven mode of cavities in RKA is proposed, and the triaxial output cavity is designed and simulated with particle in cell (PIC), which depresses self-excited oscillation and enhances the efficiency of RKA.The S-band RKA is designed according to above theoretical studies, which is also verified by PIC codes. The geometrical and electrical parameters of cavities are obtained by Mafia code. The structure and the working parameters of RKA are also optimized by PIC code.The experiment includes structural design and parameter adjustment of cavities and antenna, as well as the modulation measurement of electron beams and output microwave. The asymmetric modes of input cavity and output cavity are significantly redued, whose resonance frequency and loaded Q value meet with the design. These structures