Can Substorm Particle Acceleration Be Applied to Solar Flares?
Can Substorm Particle Acceleration Be Applied to Solar Flares?
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DOI：
10.3847/1538-4357/aa8ad4
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发表时间：
2017-10-20
影响因子：
4.9
通讯作者：
Neukirch, T.
中科院分区：
文献类型：
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作者：
Birn, J.;Battaglia, M.;Neukirch, T.
利用磁重联三维磁流体动力学 (MHD) 模拟电磁场中的测试粒子研究，我们研究了标准两带耀斑图背景下带电粒子的赋能，类似于标准磁层亚暴范式。特别是，我们研究了重联点下方塌缩场（“塌缩磁陷阱”）的影响，这已被证明是导致在与亚暴和其他脉冲事件相关的地球磁尾中观察到的高能粒子加速和注入的主要加速机制。我们将最初无力的高剪切场（低β）与低和中等剪切的有限压力（高β）拱廊结构进行对比，其中β代表气体（等离子体）和磁压力之间的比率。我们证明，激励会影响大量粒子，但在存在显着剪切场的情况下，加速度是适度的。如果不考虑损耗机制，不同能量对粒子的影响是相似的，类似于绝热加热，因此不太可能在（加热或未加热）麦克斯韦速度分布上产生幂律尾部。
Using test particle studies in the electromagnetic fields of three-dimensional magnetohydrodynamic (MHD) simulations of magnetic reconnection, we study the energization of charged particles in the context of the standard two-ribbon flare picture in analogy to the standard magnetospheric substorm paradigm. In particular, we investigate the effects of the collapsing field ("collapsing magnetic trap") below a reconnection site, which has been demonstrated to be the major acceleration mechanism that causes energetic particle acceleration and injections observed in Earth's magnetotail associated with substorms and other impulsive events. We contrast an initially force-free, high-shear field (low beta) with low and moderate shear, finite-pressure (high-beta) arcade structures, where beta represents the ratio between gas (plasma) and magnetic pressure. We demonstrate that the energization affects large numbers of particles, but the acceleration is modest in the presence of a significant shear field. Without incorporating loss mechanisms, the effect on particles at different energies is similar, akin to adiabatic heating, and thus is not a likely mechanism to generate a power-law tail onto a (heated or not heated) Maxwellian velocity distribution.