The macrodynamics of α-effect dynamos in rotating fluids
The macrodynamics of α-effect dynamos in rotating fluids
复制标题
旋转流体中α效应发电机的宏观动力学
DOI：
10.1017/s0022112075000390
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发表时间：
1975
影响因子：
3.7
通讯作者：
M. Proctor
中科院分区：
文献类型：
--
作者：
W. V. R. Maekus;M. Proctor
过去对导电流体中强迫小规模运动的大规模后果的研究导致了“α效应”发电机的产生。已经探索了这些发电机的各种线性运动学方面，表明它们在解释观测到的行星和恒星磁场方面的价值。然而，具有全局边界条件的大尺度磁场不可能是无力的，一般情况下，随着它们的增长，会引起大范围的运动。本文研究了旋转系统中整体磁场及其引起的大尺度流动的有限幅值行为。一般而言，粘性和欧姆耗散机制都在决定流动和演化磁场的幅度和结构方面发挥作用。在欧姆损失是主要耗散的情况下，发现地转流的确定是解决基本稳定性问题的重要部分。该理论的非线性方面包括与旋转无关的流动幅度和与旋转成正比的总磁能。常数a是显示行星发电机稳定机构的各种动态平衡的最简单的例子。对这种情况进行了详细的分析，以确定旋转球体内的场和流动的初始平衡。
Past study of the large-scale consequences of forced small-scale motions in electrically conducting fluids has led to the ‘α-effect’ dynamos. Various linear kinematic aspects of these dynamos have been explored, suggesting their value in the interpretation of observed planetary and stellar magnetic fields. However, large-scale magnetic fields with global boundary conditions can not be force free and in general will cause large-scale motions as they grow. I n this paper the finite amplitude behaviour of global magnetic fields and the large-scale flows induced by them in rotating systems is investigated. In general, viscous and ohmic dissipative mechanisms both play a role in determining the amplitude and structure of the flows and magnetic fields which evolve. In circumstances where ohmic loss is the principal dissipation, it is found that determination of a geo- strophic flow is an essential part of the solution of the basic stability problem. Nonlinear aspects of the theory include flow amplitudes which are independent of the rotation and a total magnetic energy which is directly proportional to the rotation. Constant a is the simplest example exhibiting the various dynamic balances of this stabilizing mechanism for planetary dynamos. A detailed analysis is made for this case to determine the initial equilibrium of fields and flows in a rotating sphere.