NONLINEAR COUPLING OF TEARING FLUCTUATIONS IN THE MADISON SYMMETRICAL TORUS

被引:19
作者
SARFF, JS
ASSADI, S
ALMAGRI, AF
CEKIC, M
DENHARTOG, DJ
FIKSEL, G
HOKIN, SA
JI, H
PRAGER, SC
SHEN, W
SIDIKMAN, KL
STONEKING, MR
机构
[1] University of Wisconsin, Madison
来源
PHYSICS OF FLUIDS B-PLASMA PHYSICS | 1993年 / 5卷 / 07期
关键词
D O I
10.1063/1.860741
中图分类号
O35 [流体力学]; O53 [等离子体物理学];
学科分类号
070204 ; 080103 ; 080704 ;
摘要
Three-wave, nonlinear, tearing mode coupling has been measured in the Madison Symmetric Torus (MST) reversed-field pinch (RFP) [Fusion Technol. 19, 131 (1991)] using bispectral analysis of edge magnetic fluctuations resolved in ''k-space.'' The strength of nonlinear three-wave interactions satisfying the sum rules m1+m2=m3 and n1+n2=n3 is measured by the bicoherency. In the RFP, m=1, n approximately 2R/a (6 for MST) internally resonant modes are linearly unstable and grow to large amplitude. Large values of bicoherency occur for two m=1 modes coupled to an m=2 mode and the coupling of intermediate toroidal modes, e.g., n=6 and 7 coupled to n=13. These experimental bispectral features agree with predicted bispectral features derived from magnetohydrodynamic (MHD) computation. However, in the experiment, enhanced coupling occurs in the ''crash'' phase of a sawtooth oscillation concomitant with a broadened mode spectrum suggesting the onset of a nonlinear cascade.
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收藏
页码:2540 / 2545
页数:6
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