太空電漿中電流片附近磁場結構之暫態變化與電漿加熱與加速過程的數值模擬研究; A Simulation Study of the Transient Magnetic Field Reconfiguration and Plasma Heating and Accelerations in the Vicinity of Electric Current Sheets in the Space Plasmas

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题名:	太空電漿中電流片附近磁場結構之暫態變化與電漿加熱與加速過程的數值模擬研究;A Simulation Study of the Transient Magnetic Field Reconfiguration and Plasma Heating and Accelerations in the Vicinity of Electric Current Sheets in the Space Plasmas
作者:	呂凌霄
贡献者:	太空科學研究所
关键词:	電流片;暫態變化;磁場線重聯;磁流體;電漿動力過程;數值模擬;electric current sheet;transient variations;magnetohydrodynamics;plasmakinetic processes;numerical simulations;plasma heating and accelerations;太空科技;物理類
日期:	2010-07-01
上传时间:	2010-06-21 10:55:45 (UTC+8)
出版者:	行政院國家科學委員會
摘要:	電流片為太空電漿中最常見的一種磁流體不連續面。這是因為大尺度磁流體電漿之磁通量凍結特性，使得來自兩個不同區域的電漿磁場無法輕易地混合，於是在它們的交界面上，就形成了厚度為中小尺度的電流片。這些電流片結構的暫態變化（例如：磁場線重聯事件），在太空電漿之能量轉換過程中，扮演著非常重要的角色。由於電流片的厚度非常薄，因此電漿動力過程在電流片暫態過程中，所扮演的角色也就顯得格外重要了。另一方面，由於大尺度磁流體的運動，則是維持電流片結構的主要能量來源，因此我們相信，大尺度電漿流的運動應該會影響整個電流片暫態變化的發展過程。本研究的目的就是要利用數值模擬研究了解（一）大尺度電漿運動對整個電流片暫態變化的影響，（二）引發電流片暫態變化的中小尺度電漿動力過程，以及這些過程所造成之電漿加熱與加速的情形。 Electric current sheets are commonly observed in the space plasma. The electric current sheet is one of the magnetohydrodynamic (MHD) discontinuities. Formation of the electric current sheet is a nature consequence of the frozen-in-flux condition of the MHD plasma. The frozen-in-flux condition prohibits the mixing of plasma and magnetic field from two different regions. As a result, electric current sheet with thickness comparable to the ions' characteristic length can be formed at the boundary of the magnetic field from two different regions. The transient variations of the electric current sheet structures (such as the magnetic reconnection events) play an important role in the energy transport in the space plasma. Since the thickness of the electric current sheet is much less than the scale length that can be described by the MHD plasma model, it is necessary to consider the plasma kinetic effects in studying the transient variations of the electric current sheet structures. On the other hand, since the electric current sheet structures are maintained by the large-scale (MHD-scale) plasma motion, we believe that the MHD-scale plasma motion should play an important role in determine the global distribution and long-term variations of the transient event of the electric current sheet. The objectives of this simulation study have twofold: (1) to understand how the large scale plasma flow affect the evolutions of the transient event of the current sheet structure, (2) to figure out the kinetic process that can lead to the onset of the transient event and the kinetic processes that can lead to plasma heating and accelerations during the transient events. 研究期間 : 9808 ~ 9907
關聯:	財團法人國家實驗研究院科技政策研究與資訊中心
显示于类别:	[太空科學研究所 ] 研究計畫

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