| Autor: |
Sarff, J. S., Assadi, S., Almagri, A. F., Cekic, M., Den Hartog, D. J., Fiksel, G., Hokin, S. A., Ji, H., Prager, S. C., Shen, W., Sidikman, K. L., Stoneking, M. R. |
| Předmět: |
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| Zdroj: |
Physics of Fluids B: Plasma Physics; Jul93, Vol. 5 Issue 7, p2540, 6p |
| Abstrakt: |
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 m[sub 1]+m[sub 2]=m[sub 3] and n[sub 1] + n[sub 2] = n[sub 3] is measured by the bicoherency. In the RFP, m=1, n∼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 magnetohydrodynamie (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. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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