Spatio-temporal dynamics of turbulence trapped in geodesic acoustic modes

Sasaki, M.; Kobayashi, Tatsuya; Itoh, K.; Kasuya, Naohiro; Kosuga, Y.; Fujisawa, A.; Itoh, Sanae–I.

doi:10.1063/1.5008541

Cited by 21 publications

(35 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The nonlinear regime with an established GAM has been described by Sasaki (2018) and Sasaki et al (2018 a , b ). An extreme in the flow can act as a trap in phase space for turbulent cells.…”

Section: Discussionmentioning

confidence: 99%

“…The GAMs have a radial phase velocity that the slab Euler equation does not have, which also scales with the magnetic drift velocity. When the radial motion of turbulent structures matches that of the GAM, the turbulent wave gets trapped inside the GAM (Sasaki 2018;Sasaki et al 2018b). The coupled system is unstable and features travelling solutions (Sasaki et al 2016(Sasaki et al , 2018a.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Investigation of tokamak turbulent avalanches using wave-kinetic formulation in toroidal geometry

et al. 2021

View full text Add to dashboard Cite

The interplay between toroidal drift-wave turbulence and tokamak profiles is investigated using a wave-kinetic description. The coupled system is used to investigate the interplay between marginally stable toroidal drift-wave turbulence and geodesic acoustic modes (GAMs). The coupled system is found to be unstable. Notably, the most unstable mode corresponds to the resonance between the turbulent wave radial group velocity and the GAM phase velocity. For a low-field-side ballooned drift-wave growth, a background flow shear breaks the symmetry between inwards- and outwards-travelling instabilities. Although this turbulence–GAM coupling may not be the primary driver for avalanches in standard core ion temperature gradient simulations, this mechanism is generic and displays many of the expected features, and should be of interest in several other regimes, which include towards the edge or in the presence of energetic particles.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigation of tokamak turbulent avalanches using wave-kinetic formulation in toroidal geometry

et al. 2021

View full text Add to dashboard Cite

show abstract

“…We can compare this model with that of Ref. [28]. The main difference is the presence of the nonlinear part of the growth-rate in our model, second term on the r.h.s.…”

mentioning

confidence: 86%

“…We extend the wave-kinetic formalism [26,27,28], to include zonal profile corrugations, i.e. zonal density.…”

mentioning

confidence: 99%

Zonal profile corrugations and staircase formation: Role of the transport crossphase

Leconte

Kobayashi

2021

Physics of Plasmas

Self Cite

View full text Add to dashboard Cite

Recently, quasi-stationary structures called E × B staircases were observed in gyrokinetic simulations, in all transport channels [Dif-Pradalier et al. Phys. Rev. Lett. 114, 085004 (2015)]. We present a novel analytical theory -supported by collisional drift-wave fluid simulations -for the generation of density profile corrugations (staircase), independent of the action of zonal flows: Turbulent fluctuations self-organize to generate quasistationary radial modulations ∆θ k (r, t) of the transport crossphase θ k between density and electric potential fluctuations. The radial modulations of the associated particle flux drive zonal corrugations of the density profile, via a modulational instability. In turn, zonal density corrugations regulate the turbulence via nonlinear damping of the fluctuations.

show abstract

“…The poloidal flows, such as zonal flows [1] and the mean flow [2,3], contributes to the turbulence suppression due to their shears [4]. Recently, not only the shear of the flow but also the curvature of the flow has been reported to be important for the turbulence suppression [5][6][7][8]. On the other hand, the toroidal flow strongly affects the MHD stability [9], so that the driving mechanisms of the toroidal flow has been intensively investigated [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Turbulence Simulation on Zonal Flow Formations in the Presence of Parallel Flows

Sasaki

Kasuya

Kosuga

et al. 2019

Plasma and Fusion Research

View full text Add to dashboard Cite

It is demonstrated that the zonal flow is controlled by the parallel flow in the cylindrical plasmas. A threedimensional turbulence simulation is performed, based on the reduced fluid model. The background parallel flow is applied by introducing the time independent parallel momentum source. Changing the magnitude of the momentum source, the behavior of the zonal flow is investigated. The drift wave turbulence is affected by the parallel flow, and it shows the spatial competition between turbulence modes. The spatial competition appears/disappears abruptly, depending on the intensity of the parallel momentum source. As a consequence of the transition between the turbulence state, the radial profile of the turbulence drastically changes, which leads to the change of the turbulence force to drive the zonal flow. In this way, the parallel flow indirectly affects the zonal flow through the deformation of the turbulence.

show abstract

Spatio-temporal dynamics of turbulence trapped in geodesic acoustic modes

Cited by 21 publications

References 33 publications

Investigation of tokamak turbulent avalanches using wave-kinetic formulation in toroidal geometry

Investigation of tokamak turbulent avalanches using wave-kinetic formulation in toroidal geometry

Zonal profile corrugations and staircase formation: Role of the transport crossphase

Turbulence Simulation on Zonal Flow Formations in the Presence of Parallel Flows

Contact Info

Product

Resources

About