Turbulent transport caused by electron temperature gradient (ETG) modes was investigated by means of gyrokinetic simulations. It was found that the ETG turbulence can be regulated by meso-scale zonal flows driven by trapped electron modes (TEMs), which are excited with much smaller growth rates than those of ETG modes. The zonal flows of which radial wavelengths are in between the ion and the electron banana widths are not shielded by trapped ions nor electrons, and hence they are effectively driven by the TEMs. It was also shown that an E x B shearing rate of the TEM-driven zonal flows is larger than or comparable to the growth rates of long-wavelength ETG modes and TEMs, which make a main contribution to the turbulent transport before excitation of the zonal flows. (C) 2014 AIP Publishing LLC.
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Univ Colorado, Boulder, CO 80309 USA
Nanchang Univ, Inst Space Sci & Technol, Nanchang 330031, Jiangxi, Peoples R ChinaUniv Colorado, Boulder, CO 80309 USA
Chen, Haotian
Tirkas, Stefan
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Univ Colorado, Boulder, CO 80309 USAUniv Colorado, Boulder, CO 80309 USA
Tirkas, Stefan
Parker, Scott E.
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Univ Colorado, Boulder, CO 80309 USAUniv Colorado, Boulder, CO 80309 USA
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Univ Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3PU, England
Univ Oxford Merton Coll, Oxford OX1 4JD, EnglandUniv Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3PU, England
Schekochihin, A. A.
Ivanov, P. G.
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Univ Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3PU, EnglandUniv Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3PU, England
Ivanov, P. G.
Roach, C. M.
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United Kingdom Atom Energy Author, Culham Ctr Fus Energy, Abingdon OX14 3DB, Oxon, EnglandUniv Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3PU, England