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Li, J.; Kishimoto, Yasuaki
Physics of Plasmas, 11(4), p.1493 - 1510, 2004/04
Times Cited Count:59 Percentile:85.15(Physics, Fluids & Plasmas)The electron temperature gradient (ETG) driven turbulence in tokamak core plasmas is numerically investigated based on three-dimensional gyrofluid model with adiabatic ion response. Attentions are focused on the zonal flow dynamics in ETG fluctuations and the resultant electron heat transport. A high electron energy confinement mode is found in the weak magnetic shear regime, which is closely relevant with self-organization behavior of turbulence through the enhanced zonal flow dynamics rather than the weak shear stabilization of ETG fluctuations. It is demonstrated that the weak shear is favorable for the enhancement of zonal flows in ETG turbulence.
Li, J.; Kishimoto, Yasuaki
Physical Review Letters, 89(11), p.115002_1 - 115002_4, 2002/09
Times Cited Count:32 Percentile:77.28(Physics, Multidisciplinary)Interaction between small-scale zonal flows and large-scale turbulence is investigated. The key mechanism is identified as radially non-local mode coupling. Fluctuating energy can be non-locally transferred from the unstable longer to stable or damped shorter wavelength region, so that turbulence spectrum is seriously deformed and deviated from the nonlinear power law structure. Three-dimensional gyro-fluid ion temperature gradient (ITG) turbulence simulations show that an ion transport bursting behavior is consistently linked to the spectral deformity with the causal role of ITG-generated zonal flows in tokamak plasmas.
Li, J.; Kishimoto, Yasuaki
Physics of Plasmas, 9(4), p.1241 - 1254, 2002/04
Times Cited Count:37 Percentile:72.43(Physics, Fluids & Plasmas)Zonal flows can be generated by drift wave turbulence through the nonlinear interactions. 3-D gyrofluid simulations show that in a turbulent system driven by electrostatic sheared slab electron temperature gradient(ETG) modes, the excitation of zonal flows is a slower process that indicates the amplitudes grow up approximately proportionally to time. The zonal flows are very weak comparing with the background turbulence and hardly work for suppressing the turbulent electron heat transport. The dynamics of zonal flows is numerically explored through starting zonal flow component in the quasi-steady state.