開口式共振腔之特性探討與數值模擬

A Study on the Spectra of Open Cavities and Numerical Simulation

劉乙力(Yi-Li Liu)

指導教授 ： 朱國瑞

國立臺灣大學/理學院/應用物理研究所/碩士(2016年)

https://doi.org/10.6342/NTU201600872

摘要

論文的內容主要圍繞著開口式共振腔，開口式共振腔常用於磁旋震盪管和磁旋調速管中。在電子束通過其開口端的期間，開口式共振腔可以有效率的得到電子束產生的電磁場。
開口式共振腔與閉口式共振腔，兩者的差別在於開口式共振腔缺乏明確的邊界條件，因此無法如閉口式共振腔一般求出解析解，因此，我們利用Cavity以及RFS2兩個程式做數值模擬，從中了解物理現象及意義。
本文從時域模型和頻域模型的理論介紹切入，在時域模型中我們藉由改變主腔體長度，以及改變傾斜角度探討對共振頻率以及品質因子的影響。在頻域模型中我們介紹最大場強法、總場能法與反射法的結果與時域模型的差異，並提出物理解釋，接著改變各種變數並計算反射系數，並觀察改變變數對反射率的影響。
最後我們嘗試模擬新的結構，並對結果提出適當的物理解釋，同時將結果與典型的開口式共振腔相比較，確認是否一致。

關鍵字

開口式共振腔 ； 共振頻率 ； 品質因子最大場強法 ； 總場能法 ； 反射法

並列摘要

The main contents of this thesis around the open cavity, open cavities are commonly used in gyromonotron oscillators and gyroklystron. During the electron beam through the open end, open cavities can get EM-field of electron beam efficiently
Open cavities and closed cavity, are different from that open cavities does not have well-defined boundary conditions, so there has not analytical solution. So, we use two programs Cavity and RFS2 to do numerical simulation to know physical phenomena and significance
We started from the introduction of time-domain model and spectral-domain model. In the time domain model, by change the length and taper angle, to know the influences of Quality factor. In the spectral-domain we introduce max-field spectrum, field-energy spectrum and reflection spectrum, and give physical explanations then change some variable and calculate reflection coefficient, to know the influence.
In the last, we try to simulate new structure, and make some appropriate physical interpretation, and compare our result to the classic open cavity, to confirm the result is identical or not.

並列關鍵字

open cavity ； resonant frequency ； quality factor ； max-field spectrum ； field-energy spectrum ； reflection spectrum

參考文獻

[1] K. R. Chu, “Time Domain Analysis of Open Cavity”, Tsing Hua University, Taiwan, R.O.C. (1993)

[2] K. R. Chu, C. S. Kou, J. M. Chen, Y. C. Tasi, C. Cheng, S. S. Bor, and L. H. Chang, “Spectral Domain Analysis of Open cavities,” Int. J. Infrared and Millimeter Wave, vol. 13, pp.1571-1598, 1992.

[3] J. D. Jackson, “Classical Electrodynamics”, John Wiley & Son, Inc., p.p. 352-374 (1998)

[5] 盧姿穎, “開口式共振腔頻譜特性之研究”, 台灣大學碩士論文, (2015)

[4] J. Mathews and R. L. Walker, “Mathematical Methods of Physics”, Addison-Wesley Publishing Company, Inc., p.p. 178-187 (1970)