Turbulence-driven zonal flows in helical systems with radial electric fields

Journal Article · Fri May 15 04:00:00 EDT 2009 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.3077274· OSTI ID:21277152

Sugama, H; Watanabe, T -H ^[1]

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1. National Institute for Fusion Science, Toki 509-5292, Japan and The Graduate University for Advanced Studies, Toki 509-5292 (Japan)

Collisionless long-time responses of the zonal-flow potential to the initial condition and turbulence source in helical systems having radial electric fields are derived theoretically. All classes of particles in passing, toroidally trapped, and helical-ripple-trapped states are considered. The transitions between the toroidally trapped and helical-ripple-trapped states are taken into account while solving the gyrokinetic equation analytically by taking its average along the particle orbits. When the radial displacements of helical-ripple-trapped particles are reduced either by neoclassical optimization of the helical geometry lowering the radial drift or by strengthening the radial electric field E{sub r} to boost the poloidal rotation, enhanced zonal-flow responses are obtained. Under the identical conditions on the magnitude of E{sub r} and the magnetic geometry, using ions with a heavier mass gives rise to a higher zonal-flow response, and therefore the turbulent transport is expected to show a more favorable ion-mass dependence than the conventional gyro-Bohm scaling.

• OSTI ID: 21277152
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 5 Vol. 16; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ELECTRIC FIELDS
IONS
PLASMA
ROTATION
TRAPPING
TURBULENCE