Charged-particle acceleration in a reconnecting current sheet including multiple magnetic islands and a nonuniform background magnetic field
Charged-particle acceleration in a reconnecting current sheet including multiple magnetic islands and a nonuniform background magnetic field
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包括多个磁岛和不均匀背景磁场的重连电流片中的带电粒子加速
DOI：
10.1051/0004-6361/201630026
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发表时间：
2017-09
影响因子：
6.5
通讯作者：
林隽
中科院分区：
文献类型：
--
作者：
李燕;吴宁;林隽
上下文带电粒子在太阳耀斑中被加速到高能量。虽然我们知道磁场重联是产生高能粒子的一种重要机制，但它在加速粒子中所起的具体作用还不清楚。目标。我们调查粒子加速磁重联在电流片，包括多个岛屿和一个引导场。方法.在电晕磁场中产生的长电流片对各种等离子体不稳定性都是不稳定的，其中撕裂模是最重要的，当这些不稳定性发展时，电流片中开始形成磁岛。两个相反的过程中观察到的表：级联的大岛，以较小的，和合并的小岛成较大的。当合并发生时，两个相邻的岛之间就会发生合并重联。由合并重联引起的电场与原大尺度重联的电场相反。我们研究了这种电流片中的粒子加速，并用测试粒子方法详细地研究了电流片中电子和质子的动力学性质。结果：我们发现有些粒子可以在很短的时间内被加速到很高的能量，有些粒子（在合并重联点附近）被一次电场和二次电场来回加速和减速。粒子的运动呈现出两种不同的沿着方向运动的轨迹：一部分粒子被捕获在磁岛周围，另一部分粒子主要沿沿着开放场线逃离电流片。两种物质的能谱都遵循双幂律形状。幂律谱中较软的成分是由于被捕获并在磁岛周围循环的粒子，而逃逸并部分被捕获的粒子则有助于谱中较硬的成分。最后，我们还研究了重联过程参数对谱特征的影响。
Context. Charged particles are accelerated to high energies in solar flares. Although we know that magnetic reconnection is an ecient.mechanism in generating energetic particles, the detailed role it plays in accelerating particles is still unknown..Aims. We investigate particle acceleration by magnetic reconnection in the current sheet, including multiple islands and a guide field..Methods. The long current sheet produced by the disruption in the corona magnetic field is usually not stable to various plasma.instabilities, among which the tearing mode is the most important, and magnetic islands start to form in the current sheet when.these instabilities develop. Two reverse processes are typically observed in the sheet: cascading of large islands to smaller ones,.and merging of small islands into larger ones. Coalescent reconnection consequently takes place between two adjacent islands when.merging occurs. The electric field induced by the coalescent reconnection is opposite to the electric field of the primary large-scale.reconnection. We studied particle acceleration in such a current sheet and examined in detail the dynamic properties of electrons and.protons in the current sheet through test particle approach..Results.We found that some particles can be accelerated to high energies in a very short time, and some particles (near the coalescence.reconnection site) are accelerated and decelerated back and forth by the primary and secondary electric fields. Particle motions show.two distinct types along dierent trajectories: some particles are trapped around magnetic islands, and some escape from the current.sheet mainly along open field lines.With the presence of a guide field, protons and electrons are found to eventually move in dierent.directions. The energy spectra for both species follow a double power-law shape. The softer components of the power-law spectrum.are due to the particles that are trapped and circulate around magnetic islands, while the particles that escape and are partly trapped.contribute to the harder component of the spectrum. Finally, we also investigated the influences of the parameters for the reconnection.process on the spectral feature.
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影响因子：
--
作者：
D. Biskamp
通讯作者：
D. Biskamp
DOI：
10.1088/0004-637x/737/1/14
发表时间：
2011-08
期刊：
The Astrophysical Journal
影响因子：
--
作者：
Chengcai Shen;Jun Lin;N. Murphy
通讯作者：
Chengcai Shen;Jun Lin;N. Murphy
影响因子：
--
作者：
D. Bruhwiler;E. Zweibel
通讯作者：
D. Bruhwiler;E. Zweibel
包括单个或多个 X 点的重新连接电流片中电子和质子的加速
DOI：
10.1007/s11207-012-9956-1
发表时间：
2012-03
期刊：
Solar flares, Magnetic reconnection, Current sheet, Energetic particles
影响因子：
--
作者：
Li, Y.;Lin, J
通讯作者：
Lin, J
影响因子：
--
作者：
A. Emslie;H. Kucharek;B. Dennis;N. Gopalswamy;G. Holman;G. Share;A. Vourlidas;T. Forbes;P. Gallagh
通讯作者：
A. Emslie;H. Kucharek;B. Dennis;N. Gopalswamy;G. Holman;G. Share;A. Vourlidas;T. Forbes;P. Gallagh