Gyrokinetic nonlinear isotope effects in tokamak plasmas

García, J.; Görler, T.; Jenko, F.; Giruzzi, G.

doi:10.1088/1741-4326/57/1/014007

Cited by 59 publications

(79 citation statements)

References 16 publications

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“…The effect of E × B shearing on the predicted heat and particle transport channels is found to be negligible for these low beta and low momentum input plasmas (while this effect may instead be sizeable in high power H-modes, see e.g. [21]), hence the mismatch in the M number profile does not invalidate the isotope identity in this case.…”

Section: Discussionmentioning

confidence: 89%

Isotope identity experiments in JET-ILW with H and D L-mode plasmas

et al. 2019

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NBI-heated L-mode plasmas have been obtained in JET with the Be/W ITER-like wall (JET-ILW) in H and D, with matched profiles of the dimensionless plasma parameters, ρ * , ν * , β and q in the plasma core confinement region and same T i /T e and Z eff . The achieved isotope identity indicates that the confinement scale invariance principle is satisfied in the core confinement region of these plasmas, where the dominant instabilities are Ion Temperature Gradient (ITG) modes. The dimensionless thermal energy confinement time, Ω i τ E,th , and the scaled core plasma heat diffusivity, A χ eff /B T , are identical in H and D within error bars, indicating lack of isotope mass dependence of the dimensionless L-mode thermal energy confinement time in JET-ILW. Predictive flux driven simulations with JETTO-TGLF of the H and D identity pair is in very good agreement with experiment for both isotopes: the stiff core heat transport, typical of JET-ILW NBI heated L-modes, overcomes the local gyro-Bohm scaling of gradient-driven TGLF, explaining the lack of isotope mass dependence in the confinement region of these plasmas. The effect of E × B shearing on the predicted heat and particle transport channels is found to be negligible for these low beta and low momentum input plasmas.

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Section: Discussionmentioning

confidence: 89%

Isotope identity experiments in JET-ILW with H and D L-mode plasmas

et al. 2019

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“…There is a stronger impact of electromagnetic effects for the DT mixture, which is strongly non-linear on , whereas for <0.1%, < &, E < &, -, at =2.5%, < &, -is nearly 30% lower than < &, . The interplay between electromagnetic effects, zonal flows and mass has been raised to explain such trend [1].…”

Section: Non-linear Gyrokinetic Analysis Of Heat Fluxmentioning

confidence: 99%

“…The different patterns in the spectrum of the heat flux, the fluctuations, the correlation length or zonal flows [1] when changing the ion mass may indicate a new way of characterizing the isotope effect by means of detailed measurements of turbulence characteristics, rather than comparison of diffusivities which rely on the calculation of power balance fluxes. The impact of the isotope effect on particle transport has been also analyzed.…”

Section: Flux Spectra and Fluctuationsmentioning

confidence: 99%

“…Recently, the benefits of high beta on thermal energy confinement have been demonstrated both in dedicated JET power scans and by means of non-linear gyrokinetic simulations, which also showed a significant impact of the fast-ion population in this turbulence reduction. Additionally, an isotope effect has been identified in such conditions due to the concomitant interplay of zonal flows, electromagnetic effects and mass, which is enhanced by the different impact of ExB flow shear on the different isotope species [1]. Therefore, a natural question is what will be the impact of a combination of all these effects on a high performance ITER plasma with a significant contribution of alpha power and how sensitive are the results on the assumptions made for the usual ITER scenario considered in the field.…”

Section: Introductionmentioning

confidence: 99%

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Isotope and fast ions turbulence suppression effects: Consequences for high-β ITER plasmas

2018

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The impact of isotope effects and fast ions on microturbulence is analyzed by means of non-linear gyrokinetic simulations for an ITER hybrid scenario at high beta obtained from previous integrated modelling simulations with simplified assumptions. Simulations show that ITER might work very close to threshold and in these conditions significant turbulence suppression is found from DD to DT plasmas. Electromagnetic effects are shown to play an important role for the onset of this isotope effect. Additionally, even external ExB flow shear, which is expected to be low in ITER, has a stronger impact on DT than in DD. The fast ions generated by fusion reactions can additionally reduce turbulence even more although the impact in ITER seems weaker than in present-day tokamaks.

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“…at high electron beta, the effect of E × B flow shear could be overestimated by quasilinear models and actually the electro magnetic stabilization be responsible for most of the reduced turbulence [9]. Recent gyrokinetic simulations for the ITER hybrid scenario show that a strong DT isotope effect can be obtained by the concomitant impact of E × B flow shear, electro magnetic effects and zonal flows [23] leading to oth erwise heat fluxes reductions similar to the one obtained with TGLF for which just the impact of E × B flow shear is the main cause of a strong isotope effect. Therefore, detailed heat fluxes comparisons between TGLF and nonlinear gyrokinetic simulations are required for properly address the isotope effect.…”

Section: Isotope and Alpha Heating Effectsmentioning

confidence: 99%

Challenges in the extrapolation from DD to DT plasmas: experimental analysis and theory based predictions for JET-DT

García

Challis

Gallart

et al. 2016

Plasma Phys. Control. Fusion

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A strong modelling program has been started in support of the future JETDT campaign with the aim of guiding experiments in deuterium (D) towards maximizing fusion energy production in Deuterium-Tritium (DT). Some of the key elements have been identified by using several of the most updated and sophisticated models for predicting heat and particle transport, pedestal pressure and heating sources in an integrated modelling framework. For the high beta and low gas operational regime, the density plays a critical role and a trend towards higher fusion power is obtained at lower densities. Additionally, turbulence stabilization by E × B flow shear is shown to generate an isotope effect leading to higher confinement for DT than DD and therefore plasmas with high torque are suitable for maximizing fusion performance. Future JET campaigns will benefit from this modelling activity by defining clear priorities on their scientific program.

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Gyrokinetic nonlinear isotope effects in tokamak plasmas

Cited by 59 publications

References 16 publications

Isotope identity experiments in JET-ILW with H and D L-mode plasmas

Isotope identity experiments in JET-ILW with H and D L-mode plasmas

Isotope and fast ions turbulence suppression effects: Consequences for high-β ITER plasmas

Challenges in the extrapolation from DD to DT plasmas: experimental analysis and theory based predictions for JET-DT

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