Zonal flows and ion temperature gradient instabilities in multiple-helicity magnetic fields

Journal Article · Sat Dec 15 04:00:00 EST 2007 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.2813182· OSTI ID:21072695

Ferrando-Margalet, S; Sugama, H; Watanabe, T -H ^[1]

---

1. National Institute for Fusion Science, Toki 509-5292 (Japan)

The effects of multiple-helicity magnetic fields on the ion temperature gradient (ITG) instability and on the zonal flow (ZF) evolution are studied with the linear gyrokinetic Vlasov code GKV [T.-H. Watanabe and H. Sugama, Nucl. Fusion 46, 24 (2006)]. The model helical fields corresponding to the standard and inward-shifted axis configurations of the Large Helical Device [O. Motojima, N. Ohyabu, A. Komori et al., Nucl. Fusion 43, 1674 (2003)] are used to investigate how ITG mode properties and ZF evolution response to a given source are influenced by the field geometry. It is shown that, in the inward-shifted configuration, the ITG mode growth rate increases slightly while the ZF is sustained for a longer time. In addition, velocity-space structures of the ion perturbed distribution function are numerically obtained which illustrate the validity of the analytical prediction that the plasma inward shift retards the radial drift of the helically trapped particles leading to the enhancement of the ZF response. This supports the conjecture that anomalous transport can be reduced by the ZF generated in the configurations optimized to decrease the neoclassical transport.

• OSTI ID: 21072695
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 12 Vol. 14; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BOLTZMANN-VLASOV EQUATION
CHARGED-PARTICLE TRANSPORT
DISTRIBUTION FUNCTIONS
ELECTRON TEMPERATURE
G CODES
HELICITY
ION TEMPERATURE
IONS
LHD DEVICE
MAGNETIC FIELDS
NEOCLASSICAL TRANSPORT THEORY
PLASMA
PLASMA CONFINEMENT
PLASMA INSTABILITY
STELLARATORS
TEMPERATURE GRADIENTS
TRAPPING
VELOCITY