【作者】 黄勇；

【导师】 李宏福；

【作者基本信息】 电子科技大学 ， 物理电子学与光电子学， 2000， 博士

【摘要】 从线性理论和非线性理论的角度，对三次谐波复合腔回旋管的高频场分布、注—波互作用、起振、模式竞争以及电子注偏心对注—波互作用的影响进行了深入细致的研究。 首先用模式耦合理论研究了渐变复合腔中高频场纵向分布所满足的普遍方程，并进行了数值求解。然后，从一般有源传输线方程出发，推导出了渐变复合腔回旋管的自洽理论模型，该理论模型考虑了复合腔过渡段中模式的耦合。在冷腔研究的基础之上，用自洽场理论模拟了三次谐波35 GHz复合腔回旋管，工作模式为TE₆₁/TE₆₂。分析了多种尺寸因素对复合腔回旋管性能的影响，优选出的腔体尺寸用于加工8mm三次谐波回旋管并进行了热测实验；探索了多种工作参数对复合腔回旋管工作性能的影响，为回旋管的热测试验提供了理论依据。 其次，在第三章中用动力学理论分析了三次谐波突变结构复合腔回旋管中的注-波互作用，选取了工作点；建立了突变复合腔回旋管的自洽非线性理论模型，该模型既考虑了电子和高频场的自洽相互作用又考虑了复合腔过渡部分模式的耦合；基于该理论模型，编写了高次回旋谐波注-波互作用计算程序，并利用该程序对三次谐波35GHz突变结构复合腔回旋管进行了数值模拟，非线性计算的结果证实和补充了动力学理论得出的结论，当电流20A，磁场为0.442T时，互作用效率为24％，输出功率为210kW。本章还用用考虑了电子注偏心的ECRM动力学理论和考虑了偏心的突变复合腔回旋管的自洽非线性理论分析了三次谐波复合腔回旋管中的注-波互作用。计算表明偏心的存在会使单一模式的起振电流增大，有可能使工作模式对H₆₁³-H₆₂³的起振电流大于寄生模式H₁₄³的起振电流，从而增大了激励起寄生模式的危险性，高次谐波模式的起振电流随偏心值起伏变化的规律比基波回旋管的情形复杂。 在第四章，首先建立了描述回旋管中多模注-互作用过程的多模非线性电子运动方程和耦合场方程，并在波导轴坐标系中将这一方程组拓展为偏心形式。文中讨论了方程组的简化和求解，并对方程中多模平均的物理意义、模式竞争和起振过程的研究方法进行了详细的讨论。然后，本文研究了偏心造成的单一模式互作用效率下降，并用起振电流的计算结果进行了解释。 电子科技大学博士论文一 在电子科技大学高stw三次谐波复合腔回旋管的实际工作条件下，采用冷腔场模型，计算了开放复合腔中工作模式和竞争模式的谐振频率。品质因素和纵向场分布：研究了在不同互作用条件和不同初始场幅值下的模式竞争清况：根据高gMt三次谐波复合腔回旋管实际工作条件下的电压、电流和a的上升过程，进行了起振过程的模拟，得到了回旋管达到的稳定工作状态。本文对通常采用的抑制模式竞争的方法进行了计算和分析，证实了采用适当电压上升方式可有效的控制模式竟争，在此基础上，研究了偏心条件下的模式竟争和起振过程，阐明了偏心对回旋管互作用的影响，不仅仅表现在偏心引起的工作模式的效率下降，也不仅：仅在于加剧回旋管中的模式竟争，而且还表赃偏心可能使使控制模式竟争的有效方法失去作用。最后，对本文中有关方法和结果进行了讨论，分析了在进一步互作用研究中采用时间相关、空间相关的完全自洽理论研究模式竞争和偏心问题的必要性。 在第五章中，分别建立了渐变结构复合腔回旋管和突变结构复合腔回旋管的多模式、多频率、时间相关的自洽非线新理论，编制了计算机模拟程序，对一只三次iw 35GHz突变结构复合腔回旋管进行了数值模拟计算中引入了一个最有可she振的竟争模式，计算结果表明，工作模式对能建立稳定的工作状态，竞争模式最终保持在噪声水平，这在一次验证了动力学理论分析的结果。更多还原

【Abstract】 This paper was mainly concerned with the nonlinear analysis and simulation of mode competitions and staitup processed in third harmonic complex cavity gyrotron. The nonlinear results were compared with those from linear theory.First, Starting from general transmission line equations with an electron beam source, a self-consistent nonlinear theoretical model for a complex cavity gyrotron with gradual transitions is presented in this paper. The model accounts for mode coupling in the transition region of the complex cavity. The interaction between the electron beam and H61-H62 RE field in the complex cavity for a third harmonic gyrotron is simulated; many calculations are carried out under different cavity dimensions and electron beam parameters.A self-consistent nonlinear theoretical model for the complex cavity gyrotron with abrupt transition is presented in this paper. The model accounts for beam loading effects self-consistently as well as mode coupling in the transition step of the complex cavity gyrotron. A field matching technique is used to treat mode conversion at the cavity step. First based on the general theory of modal expansion techniques, we got the general equations for the modal field expansion coefficients then a large waveguide step is illuminated by two sets of traveling wave from both sides. Then we directly combined out the standing wave amplitudes and their derivatives. The interaction between the electron beam and TE61,TE62 RE field in the complex cavity for a third harmonic gyrotron is simulated; nrany calculations are carried out under different electron beam parametersIn the first place, the multimode nonlinear electron motion equations and the coupling field equations were established to depict the beam-wave circumstances. We discussed in detail the simplifying and evaluation of theinteraction equations, the physical meanings of process of multimode averaging and the methods to study the mode competition and startup process. The effect of monomode efficiency decline caused by eccentricity was studied, and averaging and the methods to study the mode competition and startup process, ~vith starting current of these modes computed from linear theory to explain it.On the wrking condition of UESTC third harmonic complex cavity gyrotron , we caculated the longitudinal field profiles, resonant frequencies and Q values of the working mode and the parasitic one, using a cold cavity model.Then, we studied the mode competition statues and found possible steady states m TE611FE62 and TE14 multimode. After that, we simulated the start-up process and reached the actual steady state in UESTC gyrotmn, taking into account the actual voltage, current and a rising processes.In this paper, some mode competition controlling methods were analyzed, and the suggestion that mode selection could be realized by adopting appropriate voltage rising process was demonstrated. On the basis of the above, mode competition and startup process in eccenttic gyrotmns were studied, and the view that the eccentricity of electron beam would not only declining the interaction efficiency, not only even aggravate mode competition in gyrotrons, but also would possibly vitiate the mode competition controlling measures was clarified. The last part of the paper was devoted to the discussing of themethods used and the results obtained in this paper, and the necessity of using fully consistent, spatially and chronologically, nonlinear theory in future work was pointed out.更多还原