| 引力场中磁场重联的数值研究──（Ⅰ）磁岛的形成和合并 |
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| 引用本文： | 王水,李硕军.引力场中磁场重联的数值研究──（Ⅰ）磁岛的形成和合并[J].地球物理学报,1994,37(2):137-146. |
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| 作者姓名： | 王水 李硕军 |
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| 作者单位： | 中国科学技术大学地球和空间科学系, 合肥 230026 |
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| 摘 要： | 数值研究了引力场中电阻撕裂模不稳定性所引起的磁场重联，结果表明，在电流片长度Ｌ＝１Ｈ、半宽度δ＝Ｈ／２４的情况下，电流片两端附近将出现两个Ｘ线的磁场重联，并形成磁岛和高温高密度的等离子体团．磁岛宽度随着时间而增长，在ｔ≈５５τＡ时达到饱和，最大饱和岛宽约为４δ．同时从ｔ≈３７τＡ开始，磁岛中心位置逐渐下降；在ｔ＝５７τＡ时发生结合不稳定性，磁岛与底部附近的闭合磁场区合并，导致磁场湮灭和磁能的快速释放．另一方面，由于引力场和等离子体非均匀性的影响，顶部附近随时间而增长的等离子体外流速度达１．１４ＶＡ∞；磁岛中等离子体向下运动的最大速度达１．４１ＶＡ∞，且大于局地声速；在磁岛前方可形成快激波．这些结果可用于解释双带耀斑中后随耀斑环的形成、磁场湮灭和磁能释放、以及Ｄｏｐｐｌｅｒ速度图上观测到的红移现象．
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| 关 键 词： | 磁场重联 引力场 太阳耀斑 |
| 收稿时间： | 1993-03-03 |
NUMERICAL STUDIES FOR MAGNETIC RECONNECTION IN A GRAVITATIONAL FIELD（I）.FORMATION AND MERGING OF THE MAGNETIC ISLANDS |
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| WANG SHUI,LI SHUO-JUN,ZHBNG HUI-NAN.NUMERICAL STUDIES FOR MAGNETIC RECONNECTION IN A GRAVITATIONAL FIELD（I）.FORMATION AND MERGING OF THE MAGNETIC ISLANDS[J].Chinese Journal of Geophysics,1994,37(2):137-146. |
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| Authors: | WANG SHUI LI SHUO-JUN ZHBNG HUI-NAN |
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| Institution: | Department of Earth and Space Science, University of Science and Technology of China, Hefei 230026 |
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| Abstract: | In this paper,a magnetic reconnection caused by the resistance tearing instability in a gravitational field has been studied numerically.The results show that the magnetic reconnection with two X lines existed near the two ends of the current sheet, which has the length L-1H and the half-width δ-H/24,occured,and the magnetic island and the plasmoid with high temperature and high density formed.The magnetic island width increases with the time.A t≈55τＡ the magnetic island width approaches the saturation and the maximum width is about 4δ.At the same time , from t≈37τＡ the center position Of magnetic island dropes gradually, and at t≈57τＡ the coalescence instsbility happened. This leads to the merging of magnetic island with the closed region of magnetic field near the bottom of computational domain,and causes the annihilation of magnetic field and the rapid release of magnetic energy.On the other hand, due to the effects of the gravitational field and the plasma nonuniform, the plasma upflow velocity,which inCreases with the time, reaches 1.14ＶＡ∞ near the top of computational domain. domain. The maximum, of plasma downward velocity in the magnetic islang approches 1.14ＶＡ∞.It is larger than the local Sound Speed, and the fast Shock may be formed in front of magnetic island.These results may explain the formation of post-flare loops for the two-ribbon flares, the annihilation of magnetic field and the release of magnetic energy, and the red shift observed in the Doppler velocity map. |
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| Keywords: | Magnetic reconnection Gravitational field Solar flare |
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