Magnetic island merger as a mechanism for inverse magnetic energy transfer
Magnetic island merger as a mechanism for inverse magnetic energy transfer
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DOI：
10.1103/physrevresearch.1.012004
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发表时间：
2018-11
影响因子：
4.2
通讯作者：
Muni Zhou;Pallavi Bhat;N. Loureiro;D. Uzdensky
中科院分区：
文献类型：
--
作者：
Muni Zhou;Pallavi Bhat;N. Loureiro;D. Uzdensky
研究了连续磁岛合并引起的从小尺度到大尺度的磁能转移。一个可解的分析模型，并正确地捕捉到的主要数量的利益，证明了数值模拟的演变。磁重联被认为是实现逆转移的关键机制，并设定其属性：磁能衰减为$\tilde t^{-1}$，其中$\tilde t$是时间归一化到（适当定义的）重联时间尺度;场的相关长度增长为$\tilde t^{1/2}$。磁能谱是自相似的，并演变为$\propto \tilde t ^{-3/2}k^{-2}$，其中$k$-依赖性是由薄电流片的形成所赋予的。
Magnetic energy transfer from small to large scales due to successive magnetic island coalescence is investigated. A solvable analytical model is introduced and shown to correctly capture the evolution of the main quantities of interest, as borne out by numerical simulations. Magnetic reconnection is identified as the key mechanism enabling the inverse transfer, and setting its properties: magnetic energy decays as $\tilde t^{-1}$, where $\tilde t$ is time normalized to the (appropriately defined) reconnection timescale; and the correlation length of the field grows as $\tilde t^{1/2}$. The magnetic energy spectrum is self-similar, and evolves as $\propto \tilde t ^{-3/2}k^{-2}$, where the $k$-dependence is imparted by the formation of thin current sheets.