Effect of triangularity on ion-temperature-gradient-driven turbulence

Duff, J. M.; Faber, B. J.; Hegna, C. C.; Pueschel, M. J.; Terry, P. W.

doi:10.1063/5.0065585

Cited by 14 publications

(21 citation statements)

References 65 publications

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“…As such, adiabatic electrons are a reasonable approximation and can be effectively used to model turbulent transport. We also remark that the same numerical model was used for the analyses presented in both Duff et al (2022) and Highcock et al (2018). The latter in particular describe a plasma shape optimization process which finds that strong negative triangularity reduces turbulent transport, a conclusion in agreement with some of our results.…”

Section: The Itg Dominated Regimementioning

confidence: 94%

“…We also remark that the same numerical model was used for the analyses presented in both Duff et al. (2022) and Highcock et al. (2018).…”

Section: The Itg Dominated Regimementioning

confidence: 94%

“…2015, 2019, 2021; Duff et al. 2022) and the edge-Scrape Off Layer physics (Riva et al. 2017; Laribi et al.…”

Section: Introductionmentioning

confidence: 99%

“…Although there is an increasing amount of experimental evidence from several machines corroborating the beneficial effects of negative triangularity on confinement (Camenen et al 2007;Fontana et al 2017;Huang & Coda 2018;Marinoni et al 2019;Coda et al 2021), as well a large number of numerical studies based on those plasmas, analysing both the core (Marinoni et al 2009;Merlo et al 2015Merlo et al , 2019Merlo et al , 2021Duff et al 2022) and the edge-Scrape Off Layer physics (Riva et al 2017;Laribi et al 2021), an investigation of the interplay of negative triangularity with other plasma parameters is missing, or at least not complete. The goal of this paper is thus to attempt to partly fill this gap via gyrokinetic modelling.…”

Section: Introductionmentioning

confidence: 99%

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Interplay between magnetic shear and triangularity in ion temperature gradient and trapped electron mode dominated plasmas

Merlo

Jenko²

2023

J. Plasma Phys.

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Local gyrokinetic simulations, performed with the GENE code, are used to investigate the interaction between (negative) triangularity $\delta$ and magnetic shear $s$ , in both ion temperature gradient and trapped electron mode dominated plasmas. Magnetic shear turns out to influence in a non-trivial way the effect of negative triangularity. Also, $\delta <0$ is found to lead to a reduction of fluxes when $s>1$ but not anymore when shear is reduced. In certain parameter regimes, this effect can be inverted, up to obtaining higher fluxes when $\delta <0$ with respect to its $\delta >0$ counterpart.

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Section: The Itg Dominated Regimementioning

confidence: 94%

“…We also remark that the same numerical model was used for the analyses presented in both Duff et al. (2022) and Highcock et al. (2018).…”

Section: The Itg Dominated Regimementioning

confidence: 94%

“…2015, 2019, 2021; Duff et al. 2022) and the edge-Scrape Off Layer physics (Riva et al. 2017; Laribi et al.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Interplay between magnetic shear and triangularity in ion temperature gradient and trapped electron mode dominated plasmas

Merlo

Jenko²

2023

J. Plasma Phys.

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“…Negative triangularity (NT) provides an attractive avenue to augment the performance of RPL-modes. NT has been investigated as a means to suppress trapped electron mode turbulence dominated in TCV [96,97,98,99,100], however, recent modeling using nonlinear gyrokinetics [101,102,103] and further experimental results on TCV and DIII-D [104,105,106,107] have shown that NT may also suppress ITG turbulence in reactorrelevant regimes. Furthermore, diverted NT discharges [108,107] with low field strike points at large major radius are anticipated to have easier divertor engineering [109,110,108].…”

Section: Extrapolation To Negative Triangularitymentioning

confidence: 99%

Radiative pulsed L-mode operation in ARC-class reactors

Frank¹,

Perks²,

Nelson³

et al. 2022

Preprint

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A new ARC-class, highly-radiative, pulsed, L-mode, burning plasma scenario is developed and evaluated as a candidate for future tokamak reactors. Pulsed inductive operation alleviates the stringent current drive requirements of steady-state reactors, and operation in L-mode affords ELM-free access to ∼ 90% core radiation fractions, significantly reducing the divertor power handling requirements. In this configuration the fusion power density can be maximized despite L-mode confinement by utilizing high-field to increase plasma densities and current. This allows us to obtain high gain in robust scenarios in compact devices with P fus > 1000 MW despite low confinement. We demonstrate the feasibility of such scenarios here; first by showing that they avoid violating 0-D tokamak limits, and then by performing self-consistent integrated simulations of flattop operation including neoclassical and turbulent transport, magnetic equilibrium, and RF current drive models. Finally we examine the potential effect of introducing negative triangularity with a 0-D model. Our results show high-field radiative pulsed L-mode scenarios are a promising alternative to the typical steady state advanced tokamak scenarios which have dominated tokamak reactor development.

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Available energy of trapped electrons in Miller tokamak equilibria

Mackenbach,

Proll,

Snoep

et al. 2023

J. Plasma Phys.

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Available energy (Æ), which quantifies the maximum amount of thermal energy that may be liberated and converted into instabilities and turbulence, has shown to be a useful metric for predicting saturated energy fluxes in trapped-electron-mode-driven turbulence. Here, we calculate and investigate the Æ in the analytical tokamak equilibria introduced by Milleret al.(Phys. Plasmas, vol. 5, issue, 4, 1998, pp. 973–978). The Æ of trapped electrons reproduces various trends also observed in experiments; negative shear, increasing Shafranov shift, vertical elongation and negative triangularity can all be stabilising, as indicated by a reduction in Æ, although it is strongly dependent on the chosen equilibrium. Comparing Æ with saturated energy flux estimates from the TGLF (trapped gyro-Landau fluid) model, we find fairly good correspondence, showcasing that Æ can be useful to predict trends. We go on to investigate Æ and find that negative triangularity is especially beneficial in vertically elongated configurations with positive shear or low gradients. Furthermore, we extract a gradient-threshold-like quantity from Æ and find that it behaves similarly to gyrokinetic gradient thresholds: it tends to increase linearly with magnetic shear, and negative triangularity leads to an especially high threshold. We next optimise the device geometry for minimal Æ and find that the optimum is strongly dependent on equilibrium parameters, for example, magnetic shear or pressure gradient. Investigating the competing effects of increasing the density gradient, the pressure gradient, and decreasing the shear, we find regimes that have steep gradients yet low Æ, and that such a regime is inaccessible in negative-triangularity tokamaks.

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Effect of triangularity on ion-temperature-gradient-driven turbulence

Cited by 14 publications

References 65 publications

Interplay between magnetic shear and triangularity in ion temperature gradient and trapped electron mode dominated plasmas

Interplay between magnetic shear and triangularity in ion temperature gradient and trapped electron mode dominated plasmas

Radiative pulsed L-mode operation in ARC-class reactors

Available energy of trapped electrons in Miller tokamak equilibria

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