磁强迫系统中的负湍流磁扩散率$β$效应
Negative Turbulent Magnetic Diffusivity $β$ effect in a Magnetically Forced System
摘要：
本文研究了螺旋磁能作用下的大尺度发电机过程。磁力驱动发电机的研究不如动力驱动发电机的研究好。它被认为代表了恒星日冕、吸积盘或等离子体实验室中磁场的放大。然而，螺旋磁场和等离子体之间的相互作用是一个更基本的现象，可以扩展到早期宇宙。标度不变的螺旋磁场不仅解释了目前观测到的大尺度天体物理磁场，而且提供了早期宇宙视界标度的信息。磁场与等离子体之间的相互作用本质上是非线性的，这使得其机制难以理解。但是，如果等离子体系统是由螺旋场驱动，该过程可以线性化与α和β和大尺度磁场。传统上，α效应被认为将磁场转移到大尺度区域，而β效应扩散磁场。然而，这些结论是基于不完全导出的alpha和beta。为了得到α和\b{eta}演化的精确轮廓，我们求解了一个耦合的半解析方程组，并将结果应用于大尺度磁螺旋度和磁能的模拟数据。结果表明，在对大尺度B场的放大作出显著贡献之前，平均α效应减小。相反，保持为负的β效应实际上在具有拉普拉斯算子的大尺度B场的放大中起着关键作用。并且，这种负扩散率解释了等离子体动能的衰减
英文摘要：
We have studied the large scale dynamo process forced with helical magnetic energy. The magnetically driven dynamo is not so well studied as kinetically forced dynamo. It has been thought to represent the amplification of magnetic field in the stellar corona, accretion disk, or plasma lab. However, the interaction between the helical magnetic field and plasma is a more fundamental phenomenon that can be extended to the early Universe. The scale-invariant helical magnetic field not only explains the currently observed large scale astrophysical magnetic fields but also has information on the horizon scale in the early Universe. The interaction between magnetic field and plasma is inherently non-linear, making its mechanism difficult to understand. But, if the plasma system is driven with helical field, the process can be linearized with alpha&betaand large scale magnetic field. Conventionally, alpha effect is thought to transfer magnetic field to the large scale regime, and betaeffect diffuses magnetic field. However, these conclusions are based on the incompletely derived alpha&beta. To get the exact profiles of evolving alpha&\b{eta}, we solved a coupled semi-analytic equation set and applied the result to simulation data for the large scale magnetic helicity and magnetic energy. Our result shows that the averaged alpha effect decreases before making a significant contribution to the amplification of large scale B field. Rather, betaeffect, which keeps negative, de facto plays a key role in the amplification of large scale B field with Laplacian. And, this negative diffusivity accounts for the attenuation of plasma kinetic energy
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
