以加速器為基底的太赫茲光源能夠用於許多半導體元件材料分析以及物質非線性光譜研究中。在將加速後的電子束團壓縮至小於所預計產生的輻射波長後，我們便能將電子束打入聚頻磁鐵產生MW等級的可調聚頻磁鐵超輻射光源，利用此方法，我們能夠使用數十個MeV、束流長度為次微米範圍的電子產生太赫茲超輻射，然而在電子壓縮的過程中，電子的能散會不可避免地存在於系統中使得輻射強度下降。本論文透過撰寫一個三維聚頻磁鐵輻射程式來描述電子在聚頻磁鐵內的動力學以及輻射場，利用龍格－庫塔法追蹤電子在聚頻磁鐵內的運動，從黎納-維謝勢計算電子所產生的輻射，透過程式我們能夠探討不同條件的電子對於整體輻射所造成的效應，包含電子束團大小、電子束流長度以及能散的改變，並且與我們在國家同步輻射中心自由電子雷射測試設施中，利用U100聚頻磁鐵產生太赫茲同調聚頻磁鐵輻射的實驗結果進行驗證。

Accelerator-based intense THz radiation sources are useful for studying nonlinear and non-equilibrium states of matter in their spectral range. Tunable THz superradiant radiation of MW-level peak power can be generated from relativistic short electron beams by passing them through gap-variable undulators provided that their bunch lengths are significantly shorter than the radiation wavelengths. A few tens MeV beam of sub-picosecond bunch length suitable for generation of superradiant THz undulator emissions can easily be achieved. However, during bunch compression, beam energy spread is unavoidably introduced into the system that may deteriorate coherent THz undulator radiations. In this study, we established a three-dimensional particle tracking algorithm to analyze the electron beam dynamics under the actions of undulator and external laser field. Electron motion in the system is tracked through 4th-order Runge-Kutta method. The radiation by the beam is calculated summing up radiations from all individual electrons. Radiation fields from individual electrons are calculated directly from Lienard-Weichert potential. Furthermore, the effects of beam properties such as beam size bunch length and the energy spread are also investigated. Simulation results are in good agreement with the observation in the THz coherent undulator radiation experiment which has been performed at National Synchrotron Radiation Research Center (NSRRC) photoinjector facility with U100 planar undulator as radiator.

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