開口式共振腔之能流分析

Abstract

開口式共振腔常用於磁旋管的研究中，由於沒有明確的邊界，使得開口式共振腔的性質與閉口式共振腔的性質截然不同，也由於開口式共振腔並沒有明確的邊界條件，因此我們運用程式做數值模擬，從中了解物理的現象與意義。 本文先從時域的基礎模型出發，介紹其數學理論與所使用的邊界條件，並定義時域品質因子，探討在模型中品質因子與共振頻率的關係。接著我們討論開口式共振腔內的能量流動，透過改變共振腔體的結構以及材料性質，來分析能量的流動與消散模式，並透過電動力學推導出開口式共振腔內功率流的公式，以及使用數值模擬驗證，最後再給予適當的物理解釋。

Open cavities are commonly used in research of gyrotrons . The lack of well-defined geometrical boundary cause the distinctive features that is basically different from close cavity. Hence, we understand its physical peoperty and phenomenon by numerical simulation . We introduce the time domain models and declare the numerical algorithm and the boundary condition. The relation of quality factor and resonant frequency in time domain models is explained. We also discuss the power flow in open cavities . By changing the shapes and materials of open cavities , we analyze the flow and decay of energies. We derive the formula of power flow by electrodynamics and check our guess by numerical simulation. Finally we try to give an appropriate physical explanation for the results.