我們提出操作在TE22和TE02模式的反向反波磁旋震盪器來產生頻率連續可變的203 GHz波源作為在太赫茲頻率應用的基礎，我們負責設計電子發射源跟作用腔體並與福井大學的紅外線研究中心合作，利用他們的設備來完成實驗。我們提出的電子槍是利用非線性的電子運動來優化電子束的品質，從模擬中我們可以得到設計的電子槍在特定磁場範圍(7.4-8.0 T)以及電壓範圍下(12-22 kV)能夠產生品質良好的電子束：包含速度節距因子為1.5以及橫向速度誤差為2.8%，並擁有不錯的結構誤差容忍度。另一方面，我們提出的作用腔體利用非共振的結構來激發特定模式的高次軸向模式將輸出波源的頻寬從幾百兆赫茲加寬到幾千兆赫茲。如同CST的模擬，在固定電壓為15 kV並改變磁場的狀況下，我們實驗量測到輸出波源擁有20 GHz的可變頻寬，分別是190-196 GHz作用在TE22模式以及199-210 GHz作用在TE02模式，另外，固定磁場在7.6 T或是7.7 T並改變電壓的狀況下，我們實驗量測到輸出波源擁有2 GHz的頻寬，因此，我們提出的反向反波磁旋震盪器能夠產生非常寬頻的連續可變波源來進行太赫茲的相關研究。

We proposed a reflective gyro-BWO operated at the TE22 and the TE02 mode to generate a radiation with wide frequency-tunable range in 203 GHz for frequency-sensitive applications, such as the measurement of Ps-HFS. The experiment was carried out at the University of Fukui with a non-adiabatic electron gun and an interaction cavity designed by ourselves. The proposed electron gun takes advantage of the non-adiabatic electron motion to optimize the beam quality. Simulations predict appropriate parameters, namely the velocity pitch factor of 1.5 and the transverse velocity spread of 2.8% over wide ranges of the magnetic field (7.4-8.0 T) and the beam voltage (12-22 kV) with high structural tolerance on the cathode geometry. On the other hand, the tapered interaction cavity with the nonresonant structure is adopted to excite a series of HOAMs to broaden the bandwidth from hundreds of MHz to few GHz. Measurements show a wide bandwidth of 20 GHz with the applied beam voltage of 15 kV in the magnetic tuning as predicted by the CST simulation. The bandwidth contains two continuous frequency-tunable ranges: 190-196 GHz at the TE22 mode and 199-210 GHz at the TE02 mode. Besides, the voltage tuning results show a moderate frequency-tunable range of 2 GHz at the TE02 mode with the applied magnetic field of 7.6 T and 7.7 T, respectively. In short, the frequency-tunable radiation with the wide bandwidth suggests the proposed reflective gyro-BWO as a potential source for developing the terahertz applications.

Acknowledgements........................................i
Abstract (Chinese)......................................ii
Abstract................................................iii
Content.................................................iv
List of Figures.........................................vi
List of Tables..........................................viii

Chapter 1 Introduction..................................1
1.1 Motivation..........................................1
1.2 Introduction to Gyrotron............................2

Chapter 2 Theoretical Model for Nonlinear Simulation....7
2.1 Field Equations.....................................7
2.2 Electron Dynamics...................................9
2.3 Boundary Conditions.................................11

Chapter 3 Non-Adiabatic Electron Gun....................13
3.1 Commonly Used Parameters for an Electron Beam.......13
3.2 Theoretical Model for MIG...........................14
3.3 Non-Adiabatic Electron Gun..........................20
3.4 Practical Design of Proposed Electron Gun...........30

Chapter 4 Design of the Proposed Gyro-BWO...............33
4.1 Review of Frequency-Tunable Gyro-BWOs...............33
4.2 Transverse Modes and Oscillation Thresholds.........34
4.3 Tapered Interaction Structure.......................37
4.4 Simulation Results..................................38

Chapter 5 Experiment Setup and Results..................44
5.1 The Proposed Reflective Gyro-BWO....................44
5.2 Procedure for the Experiment........................46
5.3 Experiment Results..................................55

Chapter 6 Conclusions...................................58

References..............................................60

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