Promising High-Confinement Regime for Steady-State Fusion

Xu, G. S.; Yang, Qingquan; Niu, Y.; Wang, Y. F.; Xu, X. Q.; Guo, H.Y.; Maingi, R.; Wang, Li; Qian, J.; Gong, Xianzu; Chan, V. S.; Zhang, T.; Zang, Qing; Li, Y. Y.; Zhang, L.; Hu, G.H.; Wan, Baonian

doi:10.1103/physrevlett.122.255001

Cited by 47 publications

(64 citation statements)

References 27 publications

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“…resonant magnetic perturbation coils or pace making of smaller ELMs by pellet injection [5,6]) or even better for operational regimes that avoid such strong bursts while maintaining the good confinement at high separa-trix densities has been ongoing for years [7]. The small ELM regime presented in this work has been observed on several machines before and was then called type-II or grassy ELM regime [8][9][10][11][12][13][14]. However, at that time the interpretation of the stability of type-II ELMs took place in the same parameter space as for type-I ELMs, namely edge pressure gradient and edge bootstrap current across the whole pedestal width [15].…”

mentioning

confidence: 79%

A quasi-continuous exhaust scenario for a fusion reactor: the renaissance of small edge localized modes

Harrer,

Faitsch,

Radovanovic

et al. 2021

Preprint

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mentioning

confidence: 79%

A quasi-continuous exhaust scenario for a fusion reactor: the renaissance of small edge localized modes

Harrer,

Faitsch,

Radovanovic

et al. 2021

Preprint

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“…It has been found that the power fall-off length is larger during the QCE regime than expected from the empirical Eich scaling [8]. Other small ELM regimes that can be free of type-I ELMs include grassy ELMs (observed in JT-60U [9], JET [10], EAST and it is foreseen as a potential operational regime for CFETR [11]), type-III ELMs (not reactor-relevant because they cause confinement degradation [12]), and a low density small ELM regime in JET [13].…”

Section: Introductionmentioning

confidence: 93%

MHD simulations of small ELMs at low triangularity in ASDEX Upgrade

Cathey,

Hoelzl,

Harrer

et al. 2021

Preprint

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The development of small-and no-ELM regimes for ITER is a high priority topic due to the risks associated to type-I ELMs. By considering non-linear extended MHD simulations of the ASDEX Upgrade tokamak with the JOREK code, we probe a regime that avoids type-I ELMs completely provided that the separatrix density is high enough. The dynamics of the pedestal in this regime are observed to be qualitatively similar to the so-called quasi-continuous exhaust (QCE) regime in several ways. Repetitive type-I ELMs are substituted by roughly constant levels of outwards transport caused by peelingballooning modes (with dominant ballooning characteristics) which are localised in the last 5% of the confined region (in normalised poloidal flux). The simulated low triangularity plasma transitions to a type-I ELMy H-mode if the separatrix density is sufficiently reduced or if the input heating power is sufficiently increased. The stabilising factors that play a role in the suppression of the small ELMs are also investigated by analysing the simulations, and the importance of including diamagnetic effects in the simulations is highlighted. By considering a scan in the pedestal resistivity and by measuring the poloidal velocity of the modes (and comparing to theoretical estimates for ideal and resistive modes), we identify the underlying instabilities as resistive peeling-ballooning modes. Decreasing the resistivity below experimentally-relevant conditions (i.e., going towards ideal MHD), the peeling-ballooning modes that constrain the pedestal below the type-I ELM stability boundary display sharply decreasing growth rates.

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“…A reproducible stationary, high-confinement, small grassy ELM regimen has been demonstrated in the EAST. 49 This regimen is proposed as the primary ELM mitigation solution for the CFETR and offers a highly promising operational scenario for future steady-state fusion beyond the ITER.…”

Section: The East Project and Related Activitiesmentioning

confidence: 99%