Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, Wisconsin 53706, USA.
Phys Rev Lett. 2011 Jun 24;106(25):254502. doi: 10.1103/PhysRevLett.106.254502. Epub 2011 Jun 21.
Three-wave turbulent interactions and the role of eddy size on the turbulent electromotive force are studied in a spherical liquid-sodium dynamo experiment. A symmetric, equatorial baffle reduces the amplitude of the largest-scale turbulent eddies, which is inferred from the magnetic fluctuations spectrum (measured by a 2D array of surface probes). Differential rotation in the mean flow is >2 times more effective in generating mean toroidal magnetic fields from the applied poloidal field (via the Ω effect) when the largest-scale eddies are eliminated, thus demonstrating that the global turbulent resistivity (the β effect from the largest-scale eddies) is reduced by a similar amount.
在一个球形液态钠发电机实验中，研究了三波湍流相互作用以及旋涡大小对湍流电动势的作用。一个对称的、赤道的挡板减小了最大尺度湍涡流的幅度，这可以从磁场波动谱（由二维表面探头阵列测量）推断出来。当消除最大尺度涡旋时，平均流中的差速旋转在从施加的极向磁场（通过 Ω 效应）产生平均环向磁场方面的效率要高出 2 倍以上，从而证明了全局湍流电阻率（最大尺度涡旋的β效应）降低了大致相同的量。
