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研究生： 邱琬婷
Wan-Ting Chiu
論文名稱： 土衛六「泰坦」離子球層的化學-動力學模型
A Chemo-Dynamical Model of Titan''s Ionosphere
指導教授： 葉永烜
Wing-Huen Ip
口試委員:
學位類別： 碩士
Master
系所名稱： 理學院 - 天文研究所
Graduate Institute of Astronomy
畢業學年度： 88
語文別： 中文
論文頁數： 77
中文關鍵詞： 泰坦離子球層 、化學-動力學模型
外文關鍵詞： Titan''s ionosphere, Chemo-Dynamical Model
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    • 我們採用Andreas Kopp所發展的三維磁流體力學模型，以及實驗室的化學反應資料，並利用Yung等人根據Voyager 1觀測所建立的中性大氣結構模型，計算離子球層中，29種離子與電子反應的密度增損量，建構了一個泰坦離子球層的三維‘化學-動力學’模型，本篇論文所呈現的即是這個模型的初步結果。
    模型的結果顯示，在X-Y平面上(Y方向為往泰坦而來的電漿流向)，正對泰坦而來的電漿流的部分，電子密度的極大值（111 cm-3）出現在高度1170 km附近，主要的離子為C2H5+（50 %），及H2CN+（15%），而在尾翼的部分，H2CN+（27%）多於C2H5+（18 %）及CH3+（18 %）。在Y-Z平面上，有趣的是在尾翼的部分，我們透過三維的動力學模型可以看出，電漿是繞著泰坦及Alfvén wing流動，而非沿著高度變化。
    在電漿的產生率方面，模型中顯示電漿在尾端的總產生率為2.1×1025 s-1，與Voyager 1的觀測值相近。在解析Z-X平面上，各單位面積的產生率發現，在泰坦尾端往土星方向約0.7 RT (RT為泰坦半徑)處，電漿的產生率較附近區域來得大，這個電漿局部升高的部分，顯示泰坦的離子球層中的電漿分佈在局部地區可能有集中或空洞的存在。
    我們所發展的初步模型，將在更周延的考慮下修正電漿速度等參數值，期望在2004年Cassini號太空船抵達土星系統，對泰坦的離子球層進行探測時，我們的模型結果可以作為預測，並與之比較相互驗證。

    第一章緒言 1.1 太陽系 1.2 土星系統 1.2.1 土星 1.2.2 土星環 1.2.3 衛星 1.3 泰坦 1.3.1 大氣層 1.3.2 離子球層 1.4泰坦與土星磁球層的交互作用 1.5泰坦離子球層模型的發展 第二章CDM模型 2.1 三維磁流體力學模型 2.1.1 基本方程式 2.1.2 座標系統 2.1.3 Kopp模型之物理參數 2.1.4 MHD模擬之結果 2.2 化學反應 2.2.1 化學反應物種 2.2.2 光化學反應機制及反應係數 2.2.3 中性分子 2.3 計算方法 第三章結果與討論 3.1 X-Y平面的離子、電子密度 3.2 Y-Z平面的離子、電子密度 3.3 Z-X平面的離子、電子密度及產生率 第四章結論與展望 4.1 結論 4.2 展望 附錄 泰坦離子球層之化學反應

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