Ion-temperature-gradient modes in stellarator geometry

Rafiq, T.; Anderson, Johan; Nadeem, M

doi:10.1088/0741-3335/43/10/307

Cited by 18 publications

(22 citation statements)

References 28 publications

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“…The drift wave equation is solved by a shooting algorithm using a sixth-order Numerov scheme and WKB-type boundary conditions and by demanding continuity of the function at its first derivative at a matching point. Details of the boundary conditions and the numerical method used are given in [23].…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

Comparison of electron drift waves in numerical and analytical tokamak equilibria

Rafiq¹,

Anderson²

2003

Plasma Phys. Control. Fusion

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In this paper, we demonstrate the importance of the details of the equilibria on the stability of electron drift waves. A comparison of electrostatic electron drift waves in numerical and analytical tokamak equilibria is presented in fully three-dimensional circular and non-circular tokamaks. The numerical equilibria are obtained using the variational moments equilibrium code and the analytical equilibria used is the generalizedŝ-α model. An eigenvalue equation for the model is derived using the ballooning mode formalism and solved numerically using a standard shooting technique. The stability and the localization of the electron drift wave is found to be strongly dependent on the local shear of the magnetic field. Large values of the local shear are found to be stabilizing. A disagreement in the results is found between analytical and numerical equilibria at aspect ratios of typical tokamaks, suggesting that the latter approach should be used in the transport calculations. The effects of the local shaping of the magnetic surfaces are complicated and can be both stabilizing and destabilizing, depending on the details of the equilibria.

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Section: Numerical Results and Discussionmentioning

confidence: 99%

Comparison of electron drift waves in numerical and analytical tokamak equilibria

Rafiq¹,

Anderson²

2003

Plasma Phys. Control. Fusion

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“…The model used is an advanced fluid model for ITG modes [19] including effects of elongated flux surfaces. Previous work using this model indicates that the ITG growth is rather insensitive to the shape of the flux surface [21] - [22]. The analytical technique used here closely follow Ref.…”

Section: Introductionmentioning

confidence: 98%

Zonal flow generation in ion temperature gradient mode turbulence

et al. 2002

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In the present work the zonal flow (ZF) growth rate in toroidal ion-temperature-gradient (ITG) mode turbulence including the effects of elongation is studied analytically. The scaling of the ZF growth with plasma parameters is examined for typical tokamak parameter values. The physical model used for the toroidal ITG driven mode is based on the ion continuity and ion temperature equations whereas the ZF evolution is described by the vorticity equation. The results indicate that a large ZF growth is found close to marginal stability and for peaked density profiles and these effects may be enhanced by elongation.Comment: 20 pages, 5 figure

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“…Actually, a number of ITG modes with unconventional ballooning mode structures, characterized by peaking at arbitrary poloidal positions, have been observed in simulations [1,2,13,17,18]. These were considered as possible candidates to explain the transport in TBs.…”

Section: Introductionmentioning

confidence: 99%