Enhancement of Residual Zonal Flows in Helical Systems with Equilibrium Radial Electric Fields

Sugama, H.; Watanabe, T.‐H.

doi:10.1002/ctpp.200900006

Cited by 10 publications

(17 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Zonal flow oscillations, zonal flow damping, and even the zonal flow residual are further modified by the inclusion of a radial electric field. [32][33][34] The radial electric field drives coupling across field lines in the poloidal direction, and it is likely this would be visible in the difference between flux-tube and flux-surface calculations. Radial electric fields are not included here, and their effect on calculations in quasisymmetric devices, or in local and global geometry representations, is left for future work.…”

Section: Collisionless Zonal Flow Dampingmentioning

confidence: 99%

Comparison of local and global gyrokinetic calculations of collisionless zonal flow damping in quasi-symmetric stellarators

Smoniewski

Sánchez²,

Calvo³

et al. 2021

Physics of Plasmas

View full text Add to dashboard Cite

published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal.If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User

show abstract

Section: Collisionless Zonal Flow Dampingmentioning

confidence: 99%

Comparison of local and global gyrokinetic calculations of collisionless zonal flow damping in quasi-symmetric stellarators

Smoniewski

Sánchez²,

Calvo³

et al. 2021

Physics of Plasmas

View full text Add to dashboard Cite

show abstract

“…[17], and collisionless detrapping (producing so-called transitioning particles) was included in the theory. Numerically, the role of the ambient electric field was studied with the poloidally-global (but local in the radial direction) Eulerian code GKV in the LHD magnetic field [17,19,20]. The fullyglobal EUTERPE code has been implemented [14] in the magnetic fields of W7-X, LHD and Helically Symmetric Experiment (HSX).…”

Section: Introductionmentioning

confidence: 99%

Zonal flows in stellarators in an ambient radial electric field

Mishchenko

Kleiber

2012

Physics of Plasmas

View full text Add to dashboard Cite

show abstract

“…In a less extreme case, where f h ∼ {k 2 r δ 2 r } holds, the resulting dependence of the residual level on k r is approximately linear (see Ref. [15] for an application in the LHD device).…”

mentioning

confidence: 99%

Zonal Flow Dynamics and Control of Turbulent Transport in Stellarators

et al. 2011

Self Cite

View full text Add to dashboard Cite

The relation between magnetic geometry and the level of ion-temperature-gradient (ITG) driven turbulence in stellarators is explored through gyrokinetic theory and direct linear and nonlinear simulations. It is found that the ITG radial heat flux is sensitive to details of the magnetic configuration that can be understood in terms of the linear behavior of zonal flows. The results throw light on the question of how the optimization of neoclassical confinement is related to the reduction of turbulence.Understanding the turbulence present in tokamaks and stellarators is one of the most important challenges in plasma physics. A particularly interesting question in this context is how the magnetic geometry affects the nature and amplitude of the turbulence. In plasmas where the ion-temperature-gradient (ITG) instability is significant, so-called zonal flows (ZFs) have a favorable effect on the confinement [1]. However, the complexity introduced by nonaxisymmetry had rendered, only until very recently, the study of ZFs in stellarator configurations intractable. The dynamical character of the ZF response in a stellarator was first predicted analytically in Refs. [2,3] and was later confirmed by linear gyrokinetic simulations [4,5]. In a tokamak, the linear response to an imposed ZF perturbation consists of geodesic acoustic mode (GAM) oscillations followed by a steady state so-called Rosenbluth-Hinton (RH) residual level [6]. In stellarators, there is an intermediate stage of slow (compared with the GAM) damped ZF oscillations, and the RH residual level can be much lower than in tokamaks [3,5]. The details of this behavior depend on the magnetic configuration in question.Recent work [7] sought to reduce turbulence in stellarators by directly targeting the ITG instability. Complementing that study, here we investigate the role of ZF dynamics in regulating turbulent transport. As will become apparent, the situation is different from that in tokamaks, since the residual level is not always reached before turbulence saturates (see Figs. 4,6), and in these cases, the RH level alone cannot account for differences in the heat flux (as sometimes claimed in the tokamak literature, see e.g., Ref.[8]). Furthermore, we identify the geodesic curvature as an important ingredient affecting the ZF oscillations, viz., minimizing the geodesic curvature proves to have a significant favorable effect on the confinement. Finally, we revisit the relationship between neoclassical (nc) optimization and turbulence reduction. Although these two concepts turn out to be correlated (see also Refs. [4,9]), here we show that turbulence must be treated in addition to nc optimization. It should be remembered that turbulent transport is important in optimized stellarators, especially at low temperatures [10].As a preparatory step, to gain confidence in the numerical treatment, we present (the first published) linear and nonlinear benchmarks in stellarator geometry. Most of the presented simulations are performed with the GENE code (see, e.g., Refs. [11...

show abstract

Enhancement of Residual Zonal Flows in Helical Systems with Equilibrium Radial Electric Fields

Cited by 10 publications

References 14 publications

Comparison of local and global gyrokinetic calculations of collisionless zonal flow damping in quasi-symmetric stellarators

Comparison of local and global gyrokinetic calculations of collisionless zonal flow damping in quasi-symmetric stellarators

Zonal flows in stellarators in an ambient radial electric field

Zonal Flow Dynamics and Control of Turbulent Transport in Stellarators

Contact Info

Product

Resources

About