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Author(s):
H. Sugama and T.-H. Watanabe
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Title:
Dynamics of Zonal Flows in Helical Systems
Date of publication:
Jan. 2005
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Key words:
zonal flow, helical system, gyrokinetics
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Abstract:
Theory for describing collisionless long-time behavior of zonal flows in helical systems is presented and its validity is verified by gyrokinetic-Vlasov simulation. It is shown that, under the influence of particles trapped in helical ripples, the response of zonal flows to a given source becomes weaker for longer radial wave numbers and deeper helical ripples while a high-level zonal-flow response, which is not affected by helical-ripple-trapped particles, can be maintained for a longer time by reducing their bounce-averaged radial drift velocity. This implies a possibility that helical configurations optimized for reducing neoclassical ripple transport can simultaneously enhance zonal flows which lower anomalous transport.
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