溫度非均向性對於地球磁層頂二維結構之影響;The Effects of Temperature Anisotropy on Two-Dimensional Earth’s Magnetopause Structures

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题名:	溫度非均向性對於地球磁層頂二維結構之影響;The Effects of Temperature Anisotropy on Two-Dimensional Earth’s Magnetopause Structures
作者:	陳冠文;Chen, Guan-Wen
贡献者:	太空科學與工程研究所
关键词:	磁層頂;Grad-Shafranov 重建;磁重連;撕裂模不穩定;溫度非均向;Magnetopause;Grad-Shafranov reconstruction;Magnetic reconnection;Tearing instability;Anisotropic temperature
日期:	2020-12-29
上传时间:	2021-03-18 16:47:47 (UTC+8)
出版者:	國立中央大學
摘要:	Grad-Shafranov（GS）重建方法可以利用單一人造衛星的觀測資料，建構出空間中二維磁場與電漿磁流體力平衡結構的數值分佈，至今已被廣泛運用在重建地球磁層頂的二維結構。溫度非均向性是太空中重要的電漿特性，而過去的GS重建模式均未將此特性包含其中。本論文首次發展以描述電漿熱力狀態的double-polytropic energy closure為基礎、包含溫度非均向性之磁流體GS重建數值模式，且首度利用THEMIS （The Time History of Events and Macroscale Interactions during Substorms）與MMS （Magnetospheric Multiscale）人造衛星穿越地球磁層頂的高解析度觀測資料，重建地球磁層頂之二維磁場與電漿結構，以及探討溫度非均向性與不同的熱力狀態對於磁層頂結構的效應。研究結果顯示，溫度非均向對於磁層頂的磁島結構有顯著的效應，然對於磁重連的X-line結構較無影響。;Grad-Shafranov (GS) reconstruction method can reveal the two-dimensional magnetohydrodynamic (MHD) equilibrium plasma and magnetic field structures by using spacecraft observational data. The GS reconstruction technique has been widely applied to reconstruct the Earth’s magnetopause structures. The temperature anisotropy is an important characteristic of Earth’s space plasma environments. However, this property has not been considered in the previous GS reconstruction procedures. In this study we first develop the GS reconstruction numerical scheme with temperature anisotropy based on the double-polytropic MHD plasma models. We then apply the GS reconstruction scheme to the Earth’s magnetopause crossing events observed by the THEMIS (The Time History of Events and Macroscale Interactions during Substorms) and MMS (Magnetospheric Multiscale) spacecraft. We analyze the effects of plasma temperature anisotropy and thermodynamics on the Earth’s magnetopause structures. The reconstruction results show that the temperature anisotropy and energy closures may affect the features of magnetic islands within the magnetopause but have less effects on the magnetic reconnection with a single X-line.
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