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研究生: 劉宇倫
Yu-Lun Liou
論文名稱: 太陽閃焰硬X射線與微波觀測結合雙注入電子群之非熱輻射模擬研究
Hard X-ray and Microwave Non-thermal Emissions from Double Injection Electron Sources during a Solar Flare
指導教授: 楊雅惠
Ya-Hui Yang
口試委員:
學位類別: 碩士
Master
系所名稱: 地球科學學院 - 太空科學研究所
Graduate Institute of Space Science
論文出版年: 2018
畢業學年度: 106
語文別: 中文
論文頁數: 86
中文關鍵詞: 太陽閃焰硬X射線微波非熱輻射
外文關鍵詞: Solar, Flare, Hard X-ray, Microwave, Non-thermal Emission
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  • 太陽閃焰觀測中,硬X射線與微波之非熱輻射通常來自於高能電子的加速。本論文利用RHESSI與Nobeyama觀測站針對2014年9月23日所發生的太陽閃焰事件進行觀測與分析,並結合Fokker-Planck方程式以了解高能電子於閃焰發生時的能量分佈與變化。在RHESSI觀測中,硬X射線的輻射源位於閃焰環形結構的雙足點,而其時間變化則表現短時間的劇變。這些結果顯示硬X射線主要來自於加速的沉降電子所造成。而在Nobeyama之觀測中,微波源位於環形結構的環頂,且其時間變化在抵達峰值後則呈現緩慢遞減的趨勢。除此之外,微波峰值的時間相較於硬X射線,延遲了將近20秒之久。可推測微波輻射主要來自於環形磁場中的束縛電子。且在光譜的分析當中,雖然硬X射線與微波光譜指數於時間上皆是Soft-Hard-Harder (SHH)之變化,然而由微波推得之電子光譜指數δ_m總是小於硬X射線所推得的光譜指數δ_x。且在峰值時間的δ_m與δ_x相差3.7。這些現象解釋閃焰爆發時所產生的加速電子擁有不相同的能量分佈。
    在Fokker-Planck方程式的計算當中,我們以單冪律分佈模擬擁有相同能量分佈的注入電子,以及以雙冪律模擬擁有不同能量分佈的注入電子,藉以討論兩者不同情況下的結果,並與實際觀測做比較。研究結果中發現,以雙冪律為能量分佈的注入電子所計算的結果在光譜、輻射光變曲線中與觀測上的特徵皆有所吻合。此一結果印證2014年9月23日發生之太陽閃焰事件,其爆發所產生的加速電子擁有不同的能量分佈。


    The accelerated electrons during the impulsive phase of solar flares are commonly believed to be responsible for the non-thermal emissions in hard X-ray and microwave observations. In this study, we analyze an M2.3 flare on 2014 September 23 by combining the RHESSI and Nobeyama measurements. The non-thermal emissions in HXRs present two chromospheric footpoints, which their time profiles vary with impulsive peaks, showing that precipitating electrons are dominated in this wavelength. For microwaves, the emission burst come from the looptop, and their time variations perform extended tail after microwave peak. As well, the peak time of 17 GHz microwave was postponed by nearly 20 seconds with respect to 20-30 keV HXR peak. Those outcomes indicate microwave emissions are coming from the trapped electrons. In the spectrum analysis, the electron spectral indices δ_m derived from microwaves are always harder than these δ_x derived from HXRs. And, there is 3.7 difference between δ_m and δ_x at peak time. We suggest that the injection electrons from the acceleration region during the flare have multiple energy distribution.
    Furthermore, we verify those observations by solving the spatially homogeneous Fokker-Planck equation, which was used in Minoshima (2008). We simultaneously calculate numerical results with single and double injection electron sources, which were respectively described by the mathematical forms of single and broken power-law distribution in energy space. We found the calculated light curves and spectra from numerical outputs in both wavelengths are consistent with the observational results. The correspondence agrees with the statement that the acceleration electrons have different energy distribution during the flare on 2014 September 23.

    中文摘要 i 英文摘要 iii 致謝 v 目錄 vii 圖目錄 ix 表目錄 xi 一、 緒論 1 1.1 太陽閃焰 1 1.2 閃焰標準模型 4 1.3 高能電子之傳輸 8 1.4 非熱輻射機制與研究 11 1.4.1 韌致輻射與X射線光譜 11 1.4.2 迴旋同步輻射與微波光譜 12 1.4.3 相關研究 12 1.5 結語 15 二、 觀測與分析 16 2.1 觀測儀器 16 2.1.1 RHESSI 16 2.1.2 NoRP、NoRH 17 2.2 非熱輻射之光變曲線 17 2.3 非熱輻射之影像 25 2.4 光譜分析 27 2.4.1 硬X射線與厚靶韌致輻射光譜 28 頁次 2.4.2 微波與迴旋同步輻射光譜 30 2.5 討論與總結 33 三、 數值方法與分析 34 3.1 基本方程式與參數 34 3.2 數值計算 41 3.3 光譜指數與光變曲線之計算 43 四、 結果與討論 46 4.1 數值結果 46 4.2 觀測結果與雙冪律注入電子 56 五、 總結 59 參考文獻 61 附錄一、 數值方法與詳細計算(一) 65 附錄二、 數值方法與詳細計算(二) 70

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