Nornberg M D, Spence E J, Kendrick R D, Jacobson C M, Forest C B
Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, Wisconsin 53706, USA.
Phys Rev Lett. 2006 Jul 28;97(4):044503. doi: 10.1103/PhysRevLett.97.044503. Epub 2006 Jul 26.
The magnetic field measured in the Madison dynamo experiment shows intermittent periods of growth when an axial magnetic field is applied. The geometry of the intermittent field is consistent with the fastest-growing magnetic eigenmode predicted by kinematic dynamo theory using a laminar model of the mean flow. Though the eigenmodes of the mean flow are decaying, it is postulated that turbulent fluctuations of the velocity field change the flow geometry such that the eigenmode growth rate is temporarily positive. Therefore, it is expected that a characteristic of the onset of a turbulent dynamo is magnetic intermittency.
在麦迪逊发电机实验中测量的磁场表明，当施加轴向磁场时，会出现间歇性的增长期。间歇性磁场的几何形状与使用平均流层流模型的运动学发电机理论预测的增长最快的磁本征模一致。尽管平均流的本征模在衰减，但据推测，速度场的湍流波动会改变流场几何形状，使得本征模增长率暂时为正。因此，可以预期，湍流发电机开始的一个特征是磁间歇性。
