【作者】 刘頔威；

【导师】 刘盛纲；

【作者基本信息】 电子科技大学 ， 物理电子学， 2009， 博士

【摘要】 太赫兹辐射源技术是太赫兹科学与技术的核心之一。回旋管是目前众多太赫兹辐射源中辐射功率最大的辐射源,太赫兹回旋器件的研究对太赫兹辐射源的发展具有重要的意义。但回旋管工作频率越高,其所需的外加磁场强度也越大(工作在1THz的基波回旋器件,需外加磁场约40T,这样的强磁场体积庞大且很难实现)。采用高次回旋谐波工作的回旋器件可以大大降低对外加磁场强度的要求(工作在n次回旋谐波的回旋器件,其外加磁场减小为原来的1／n),因此,高次回旋谐波回旋管的研究在太赫兹波段显得尤为重要。本学位论文利用耦合波理论对同轴双电子注太赫兹回旋管的注波耦合机理进行了研究；利用散射矩阵理论、线性理论和自洽非线性理论,对太赫兹回旋倍频速调管的腔体设计、模式选取和注波互作用机理进行了详细的研究和讨论；利用平面波展开法,对一种新型的回旋谐振腔——光子晶体谐振腔的带隙结构计算进行了讨论；最后对作者在日本Fukui UniversityFIR研究中心参与的太赫兹回旋管的相关实验工作进行了详细的介绍并提出了同轴双电子注太赫兹回旋管和三腔太赫兹回旋倍频速调管的实验方案。1、在研究同轴双电子注回旋管注波互作用机理时,利用耦合波理论,对双频、单频工作的同轴双电子注回旋管的注波互作用机理进行了研究,并将单频、双频工作同轴双电子注回旋管与相同几何尺寸及电子注参数的同轴单电子注回旋管进行了比较。比较后发现,跟同轴单电子注回旋管相比,由于注波间的耦合作用,双频工作的同轴双电子注回旋管的两个模式都得到增强。2、对三腔太赫兹回旋倍频速调管进行了详细的研究,利用散射矩阵理论,对回旋谐振腔进行设计与分析,讨论了腔体几何结构对腔体谐振频率和品质因数的影响；利用小信号理论,讨论了回旋倍频速调管的模式选取、色散关系、起振电流及模式竞争；运用自洽非线性理论,对回旋倍频速调管的注波互作用机理进行了详细的研究,分析了电子注的调制过程,漂移区、输出腔长度、电子注电压、电流、横纵速度比和引导中心半径对互作用效率的影响,并讨论了输出腔欧姆损耗对输出功率的影响。3、在研究光子晶体谐振腔时,对二维平行四边形晶格介质柱、金属光子晶体的第一布里渊区及平面波展开法计算带隙结构进行了详细的研究,并通过对二维正三角形、方形晶格及第一布里渊区的临界条件下二维介质柱、金属光子晶体的带隙结构的计算和比较,证明了本文方法的有效性。4、对在Fukui University FIR研究中心参与的太赫兹回旋管FU CWⅡ的功率、功率随磁场变化关系、频率、波长等的测量工作进行了详细的介绍,提出了同轴双电子注太赫兹回旋管和回旋倍频速调管的实验方案。更多还原

【Abstract】 THz radiating sources is one of the key topics in THz science and technology, the gyrotron is the most powerful source among various THz sources. Study on THz gyrotron plays an important role in the development of THz sources. However, the gyrotron operating higher frequency needs stronger magnetic field (1THz gyrotrons operating at fundamental cyclotron harmonic need 40 Tesla working magnetic field, so strong magnet is expensive and difficult to fabricate). In order to reduce the strength of magnetic field, the gyrotron needs to operate at higher cyclotron harmonics (when the gyrotron working at nth cyclotron harmonic, the corresponding working magnetic field can be reduced to 1/n). Study on high cyclotron harmonic gyrotron is important in THz region. In this dissertation, the beam-wave interactions of coaxial gyrotron with two electron beams are studied with the coupled-mode theory; meanwhile, with the linear and self-consistent nonlinear theories, the beam-wave interactions and electron bunching process of three-cavity frequency-quadrupling gyroklystron are studied and discussed in details; then, a new-type of gyrotron resonant cavity-photonic crystal cavity is studied and discussed with the plane wave expansion methods; finally, the THz gyrotron experiments the author participated in at FIR Center of Fukui University is detailed introduced.1. The beam-wave interactions of coaxial gyrotron with two electron beams are studied. With the coupled-mode theory, the beam-wave interactions of dual-frequency, single-frequency coaxial gyrotron with two electron beams are discussed in details, compared to the one-electron-beam coaxial gyrotron with the same geometric structure and parameters of electron beams, due to the coupling between two beams and two modes, two modes of the dual-frequency coaxial gyrotron with two electron beams are enhanced.2. three-cavity THz frequency-quadrupling gyroklystron with successive frequency doubling in each cavity is detailed studied. The cavities are designed and analyzed with the scattering matrix methods and simulated with the CST software, the geometric parameters’ effects on the resonant frequency and quality factor of the resonant cavity are discussed; the mode selection, dispersion relation, starting current and possible competing modes are considered with the linear theory, the beam-wave interactions of three-cavity frequency-quadrupling gyroklystron are studied with the self-consistent nonlinear theory, the bunching process of electrons is studied, the effect of length of drift tubes and output cavity, voltage, current, velocity pitch and guiding center radius of electron beam on the output efficiency is discussed, meanwhile, the effect of the ohmic loss on the output efficiency is considered.3. The photonic crystal cavity is studied with the plane wave expansion methods. The first Brillouin zone and photonic band gap calculation of two-dimensional arbitrary parallelogram lattice dielectric rods and metallic photonic crystals are discussed in details. The photonic band gap structures of triangular lattice and square lattice two-dimensional photonic crystal calculated by the method described in this dissertation agree well with the conventional method, furthermore, the calculated photonic band gap in critical conditions of the first Brillouin zone are consistent with either hexagon or quadrangle Brillouin zone, which shows that the method described here is valid.4. The THz gyrotron experiment the author participated in at FIR Center of Fukui University including power spectrum, frequency, wavelength, the power measurement is introduced.更多还原