Density Fluctuation of GAM Zonal Flows on the HL-2A Tokamak
نویسندگان
چکیده
The density fluctuation of Geodesic Acoustic Mode (GAM) zonal flow has been observed in Ohmic deuterium plasma discharges with Langmuir probe arrays on the HL-2A tokamak. The density fluctuation has the poloidal mode number m < 1 and toroidal mode number n ~ 0. Its amplitude is consistent with theoretic prediction as well. Bispectral analysis shows that the nonlinear interaction between the GAM zonal flow and high frequency ambient turbulence (HFAT) is a plausible mechanism for the generation of the GAM. The phase shifts between the GAM and its envelope of the HFAT (200-450 kHz) with different poloidally separations are π/2 to π, indicating that the ambient turbulence is regulated by the GAM through envelope modulation. Keyword: Zonal flow, fluctuations, long range correlation, potential turbulence, turbulence studies
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