Zonal flow and field generation by finite beta drift waves and kinetic drift-Alfvén waves

Guzdar, P. N.; Kleva, Robert G.; Das, Amita; Kaw, P. K.

doi:10.1063/1.1386640

Cited by 25 publications

(29 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This representation is the local version of the decomposition used by Chen et al, 19 and the complex representation of that used by Guzdar. 20,21 Inserting Eq. ͑8͒ into Eqs.…”

Section: Theoretical Modelmentioning

confidence: 98%

Low to high confinement transition theory of finite-beta drift-wave driven shear flow and its comparison with data from DIII-D

et al. 2004

Self Cite

View full text Add to dashboard Cite

Shear flow stabilization of edge turbulence in tokamaks has been the accepted paradigm for the improvement in confinement observed in high (H) confinement mode plasmas. Results on the generation of zonal flow and fields in finite β plasmas are presented. This theory yields a criterion for bifurcation from low to high (L–H) confinement mode, proportional to Te/Ln, where Te is the electron temperature and Ln is the density scale-length at the steepest part of the density gradient. When this parameter exceeds a critical value (mostly determined by the strength of the toroidal magnetic field), the transition occurs. The predicted threshold based on this parameter shows good agreement with edge measurements on discharges undergoing L–H transitions in DIII-D [J. L. Luxon, R. Anderson, F. Batty et al., in Proceedings of the 11th Conference on Plasma Physics and Controlled Fusion Research, 1986 (International Atomic Energy Agency, Vienna, 1987), Vol. I, p. 159]. The observed differences in the transitions with the reversal of the toroidal magnetic field are reconciled in terms of this critical parameter due to the differences in the density gradient scale-lengths in the edge. The theory also provides a possible explanation for lowered threshold power, pellet injection H modes in DIII-D, thereby providing a unified picture of the varied observations on the L–H transition.

show abstract

“…This representation is the local version of the decomposition used by Chen et al, 19 and the complex representation of that used by Guzdar. 20,21 Inserting Eq. ͑8͒ into Eqs.…”

Section: Theoretical Modelmentioning

confidence: 98%

Low to high confinement transition theory of finite-beta drift-wave driven shear flow and its comparison with data from DIII-D

et al. 2004

Self Cite

View full text Add to dashboard Cite

show abstract

“…Motivated by the experimental discovery of a low-to-high (LH) transition in the plasma confinement, experimental and theoretical works in the two last decades have focused on whether the turbulence associated with the H-mode might be regulated by interactions with ZFs or shear flows. In particular the generation of zonal flow by finite beta drift waves or kinetic drift wave was investigated by Guzdar et al in [5,6] showing the importance of parametric-type processes in the LH transition.…”

Section: Introductionmentioning

confidence: 99%

Transport Barrier Triggered by Resonant Three-Wave Processes Between Trapped-Particle-Modes and Zonal Flow

Ghizzo

Sarto

2019

Plasma

View full text Add to dashboard Cite

We address the mechanisms underlying low-frequency zonal flow generation in a turbulent system through the parametric decay of collisionless trapped particle modes and its feedback on the stabilization of the system. This model is in connection with the observation of barrier transport in reduced gyrokinetic simulations (A. Ghizzo et al., Euro. Phys. Lett. 119(1), 15003 (2017)). Here the analysis is extended with a detailed description of the resonant mechanism. A key role is also played by an initial polarisation source that allows the emergence of strong initial shear flow. The parametric decay leads to the growth of a zonal flow which differs from the standard zero frequency zonal flow usually triggered by the Reynolds stress in fluid drift-wave turbulence. The resulting zonal flow can oscillate at low frequency close to the ion precession frequency, making it sensitive to strong amplification by resonant kinetic processes. The system becomes then intermittent. These new findings, obtained from numerical experiments based on reduced semi-Lagrangian gyrokinetic simulations, shed light on the underlying physics coming from resonant wave-particle interactions for the formation of transport barriers. Numerical simulations are based on a Hamiltonian reduction technique, including magnetic curvature and interchange turbulence, where both fastest scales (cyclotron and bounce motions) are gyro-averaged.

show abstract

“…The coherent mode coupling model used in this particular study has been adopted and fitted to this field of study in recent years [6][7][8][9][10][11][12][13][14]. It has been shown that the model is in good agreement with the corresponding model derived using the wave kinetic equation [13] and the model has successfully contributed to better understanding of the weak generation of zonal flows in recent measurements at the Columbia Linear Machine [14].…”

Section: Introductionmentioning

confidence: 85%

Quasilinear analysis of the zonal flow back-reaction on ion-temperature-gradient mode turbulence

Anderson

Kishimoto

et al. 2008

Physics Letters A

View full text Add to dashboard Cite

There is strong evidence in favor of zonal flow suppression in the Ion-Temperature-Gradient (ITG) mode turbulence, specifically close to the linear stability threshold. The present Letter attempts to analytically calculate the effects of zonal flow suppression of the ITG turbulence by deriving a modified dispersion relation including the back-reaction of the zonal flows on the ITG turbulence based on the quasilinear theory. The results are manifested in a reduction of the linear growth rate and an increase in the effective linear ITG threshold.Crown

show abstract

Zonal flow and field generation by finite beta drift waves and kinetic drift-Alfvén waves

Cited by 25 publications

References 28 publications

Low to high confinement transition theory of finite-beta drift-wave driven shear flow and its comparison with data from DIII-D

Low to high confinement transition theory of finite-beta drift-wave driven shear flow and its comparison with data from DIII-D

Transport Barrier Triggered by Resonant Three-Wave Processes Between Trapped-Particle-Modes and Zonal Flow

Quasilinear analysis of the zonal flow back-reaction on ion-temperature-gradient mode turbulence

Contact Info

Product

Resources

About