Key impact of phase dynamics and diamagnetic drive on Reynolds stress in magnetic fusion plasmas

Sarazin, Y.; Dif‐Pradalier, G.; Garbet, X.; Ghendrih, Ph.; Berger, Alexandre R.; Gillot, Camille; Grandgirard, V.; Obrejan, Kevin; Varennes, R; Vermare, Laure; Cartier-Michaud, Thomas

doi:10.1088/1361-6587/abf673

Cited by 12 publications

(12 citation statements)

References 38 publications

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“…The results of the system (38)(39)(40)(41)(42) are shown in figure 9 for the C = 1 case with k y = 1.125 [i.e. k = (0, k y ), p 1 = (−q, −k y ), p 2 = (q, −k y ) and q = (q, 0)] for q = (1.0, 1.5, 2.0, 4.0) from top to bottom respectively.…”

Section: A Triad Pairsmentioning

confidence: 99%

“…We consider a network of triad pairs as discussed in section III A, with a single value of k y and q values that go from 0.125 to 4.0 in steps of 0.125. Notice that such a network has many different types of interactions as shown in figure 10, but all of those involve one of the zonal modes, which means that if we compute the inverse Fourier transform in the x direction, the network can be seen to be equivalent to the single k y , full-x, quasi-linear model [38,39], since in both cases we have full spatial evolution but only nonlinear coupling is with the zonal flow.…”

Section: Specific Network Configurationsmentioning

confidence: 99%

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Phase and amplitude evolution in the network of triadic interactions of the Hasegawa-Wakatani system

Gürcan¹,

Anderson²,

Moradi³

et al. 2022

Preprint

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Hasegawa-Wakatani system, commonly used as a toy model of dissipative drift waves in fusion devices is revisited with considerations of phase and amplitude dynamics of its triadic interactions. It is observed that a single resonant triad can saturate via three way phase locking where the phase differences between dominant modes converge to constant values as individual phases increase in time. This allows the system to have approximately constant amplitude solutions. Non-resonant triads show similar behavior only when one of its legs is a zonal wave number. However when an additional triad, which is a reflection of the original one with respect to the y axis is included, the behavior of the resulting triad pair is shown to be more complex. In particular, it is found that triads involving small radial wave numbers (large scale zonal flows) end up transferring their energy to the subdominant mode which keeps growing exponentially, while those involving larger radial wave numbers (small scale zonal flows) tend to find steady chaotic or limit cycle states (or decay to zero). In order to study the dynamics in a connected network of triads, a network formulation is considered including a pump mode, and a number of zonal and non-zonal subdominant modes as a dynamical system. It was observed that the zonal modes become clearly dominant only when a large number of triads are connected. When the zonal flow becomes dominant as a 'collective mean field', individual interactions between modes become less important, which is consistent with the inhomogeneous wave-kinetic picture. Finally, the results of direct numerical simulation is discussed for the same parameters and various forms of the order parameter are computed. It is observed that nonlinear phase dynamics results in a flattening of the large scale phase velocity as a function of scale in direct numerical simulations.

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Section: A Triad Pairsmentioning

confidence: 99%

Section: Specific Network Configurationsmentioning

confidence: 99%

Phase and amplitude evolution in the network of triadic interactions of the Hasegawa-Wakatani system

Gürcan¹,

Anderson²,

Moradi³

et al. 2022

Preprint

View full text Add to dashboard Cite

show abstract

“…Notice that such a network has many different types of interactions as shown in Fig. 10, but all of those involve one of the zonal modes, which means that if we compute the inverse Fourier transform in the x direction, the network can be seen to be equivalent to the single k y , full-x, quasi-linear model 43,44 since in both cases we have full spatial evolution in x direction but the only nonlinear coupling is with the zonal flow.…”

Section: Network With a Single K Ymentioning

confidence: 99%

Phase and amplitude evolution in the network of triadic interactions of the Hasegawa–Wakatani system

et al. 2022

View full text Add to dashboard Cite

The Hasegawa–Wakatani system, commonly used as a toy model of dissipative drift waves in fusion devices, is revisited with considerations of phase and amplitude dynamics of its triadic interactions. It is observed that a single resonant triad can saturate via three way phase locking, where the phase differences between dominant modes converge to constant values as individual phases increase in time. This allows the system to have approximately constant amplitude solutions. Non-resonant triads show similar behavior only when one of its legs is a zonal wave number. However, when an additional triad, which is a reflection of the original one with respect to the y axis is included, the behavior of the resulting triad pair is shown to be more complex. In particular, it is found that triads involving small radial wave numbers (large scale zonal flows) end up transferring their energy to the subdominant mode which keeps growing exponentially, while those involving larger radial wave numbers (small scale zonal flows) tend to find steady chaotic or limit cycle states (or decay to zero). In order to study the dynamics in a connected network of triads, a network formulation is considered, including a pump mode, and a number of zonal and non-zonal subdominant modes as a dynamical system. It was observed that the zonal modes become clearly dominant only when a large number of triads are connected. When the zonal flow becomes dominant as a “collective mean field,” individual interactions between modes become less important, which is consistent with the inhomogeneous wave-kinetic picture. Finally, the results of direct numerical simulation are discussed for the same parameters, and various forms of the order parameter are computed. It is observed that nonlinear phase dynamics results in a flattening of the large scale phase velocity as a function of scale in direct numerical simulations.

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“…However, the turbulent transport can be greatly reduced in the presence of a stable shear flow (Terry 2000; Stroth, Manz & Ramisch 2011; Sarazin et al. 2021), which is due to the radial variation of the poloidal component of the electric cross-drift. When the shear rate is comparable to the nonlinear turbulence decorrelation rate, the turbulent motion is suppressed (Biglari, Diamond & Terry 1990; Ware et al.…”

Section: Introductionmentioning

confidence: 99%

Simulation campaign of the turbulent diffusion at the edge of fusion devices

Scarivaglione

Valentini²,

Servidio³

2023

J. Plasma Phys.

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The understanding of cross-field transport is crucial for optimizing the properties of magnetic confinement in fusion devices. In this work, a two-dimensional, simplified model is used to study the turbulent dynamics in the region of the scrape-off layer. The numerical model, based on the reduced Braginskii equations, is able to describe the formation and the evolution of blob-like structures. The dynamics has been investigated by using both classical Eulerian analysis and the Lagrangian approach, by varying the ambient conditions of the plasma. The major goals are (i) a detailed and systematic study of turbulence by varying the plasma jump conditions in the edge tokamaks plasmas and (ii) a Lagrangian diffusion study of the edge turbulence by using an appropriate Braginskii model. It has been found that both the magnetic shear and the plasma mean profiles of density and temperature are crucial for setting the properties of the transport. By following fluid tracers, diffusive transients for the radial transport are observed, at length scales larger than the typical blob size. This work is relevant for the comprehension of the turbulent transport at tokamaks edges.

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Key impact of phase dynamics and diamagnetic drive on Reynolds stress in magnetic fusion plasmas

Cited by 12 publications

References 38 publications

Phase and amplitude evolution in the network of triadic interactions of the Hasegawa-Wakatani system

Phase and amplitude evolution in the network of triadic interactions of the Hasegawa-Wakatani system

Phase and amplitude evolution in the network of triadic interactions of the Hasegawa–Wakatani system

Simulation campaign of the turbulent diffusion at the edge of fusion devices

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