Growth rates of ITG modes in the presence of flow shear

Dagnelie, Victor I.; Citrin, J.; Jenko, F.; Pueschel, M. J.; Görler, T.; Told, D.; Doerk, H.

doi:10.1063/1.5030416

Cited by 6 publications

(5 citation statements)

References 28 publications

(38 reference statements)

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“…The rotation is therefore included utilizing the τ AC approach, as presented in [68]. This method originates from the observation that the relevant timescale to average physical quantities is the nonlinear decorrelation time.…”

Section: Appendixmentioning

confidence: 99%

Integrated modelling of neon impact on JET H-mode core plasmas

Marin

Citrin²,

Giroud³

et al. 2022

Nucl. Fusion

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Nuclear fusion reactor plasmas will need to exhaust a significant proportion of energy flux through radiative processes, to enable acceptable divertor loads. This can be obtained by line radiation from impurities, injected from the plasma edge. There are however limitations on the sustainable impurity content, since radiation from the core can lead to a deleterious electron heat sink. Moreover, dilution of the main ions reduces the available fuel. Simultaneously, impurities have an impact on the turbulent transport, both by dilution and by changes in the effective charge. Recent experiments at JET point towards an improvement in plasma confinement in neon seeded discharges with respect to purer equivalent plasmas. In this paper the impact of the impurities on the confinement is studied, isolating various effects. First-principle-based integrated modelling with the QuaLiKiz quasilinear turbulent transport model explains the improvement by a combination of higher pedestal temperature, increased rotation shear, and impurity-induced microturbulence stabilization. These results are optimistic with respect to the maximum impurity levels allowed in ITER and future reactors. Comparison between QuaLiKiz and higher fidelity gyrokinetics has exposed issues with QuaLiKiz impurity peaking predictions with rotation.

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Section: Appendixmentioning

confidence: 99%

Integrated modelling of neon impact on JET H-mode core plasmas

Marin

Citrin²,

Giroud³

et al. 2022

Nucl. Fusion

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“…This rule is based on a new set of linear GENE 25 scans around the GA-Standard case, coupled to a methodology to assess the impact of rotation on linear growthrates in spite of the Floquet fluctuations. 26,27 These scans consisted of toroidal rotation scans for various q, e r R , andŝ, capturing both the effects of E Â B stabilization and Parallel Velocity Gradient (PVG) destabilization. The rule scales all ion-scale fluxes with a tuned function f rot ðq;ŝ; eÞ.…”

Section: Rotation Rulementioning

confidence: 99%

Fast modeling of turbulent transport in fusion plasmas using neural networks

et al. 2020

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“…One should note, however, that this purely linear approach cannot directly explain the situation in the tokamak pedestal, considering a simple quench rule will treat even and odd parity equivalently, and linear simulations cannot capture key physics of the toroidal E×B shear. Rather than toroidal flow shear [72,73], the present investigation focuses on parallel flow shear w = - ¶W ¶ R x pfs 0 0…”

Section: Modes In Toroidal Geometrymentioning

confidence: 99%

On microinstabilities and turbulence in steep-gradient regions of fusion devices

Pueschel

Hatch

Ernst

et al. 2019

Plasma Phys. Control. Fusion

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Higher excitation states along the background field of plasma instabilities dominate over standard, ground-state eigenmodes once the gradient drive becomes sufficiently strong. At this point, mode parity can no longer be used as the sole identifier of microtearing activity. Not only ion-and electron-temperature-gradient-driven modes occur in higher states, but even trapped electron modes, where decorrelation mechanisms enable odd-parity mode structures without a vanishing bounce average. Nonlinearly, higher-order Hermite states imprint their structures on the turbulence. Even at considerably strong drive, however, quasilinear models can recover nonlinear fluxes, as long as all subdominantly unstable eigenmodes are included. Due to flux contributions from such modes, gradient scalings of fluxes can be stronger than linear expectations.

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Growth rates of ITG modes in the presence of flow shear

Cited by 6 publications

References 28 publications

Integrated modelling of neon impact on JET H-mode core plasmas

Integrated modelling of neon impact on JET H-mode core plasmas

Fast modeling of turbulent transport in fusion plasmas using neural networks

On microinstabilities and turbulence in steep-gradient regions of fusion devices

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