The EPED pedestal model and edge localized mode-suppressed regimes: Studies of quiescent H-mode and development of a model for edge localized mode suppression via resonant magnetic perturbations

P. B. Snyder; T. H. Osborne; K. H. Burrell; R. J. Groebner; A. W. Leonard; R. Nazikian; D. M. Orlov; O. Schmitz; M. R. Wade; H. R. Wilson

doi:10.1063/1.3699623

The EPED pedestal model and edge localized mode-suppressed regimes: Studies of quiescent H-mode and development of a model for edge localized mode suppression via resonant magnetic perturbations

P. B. Snyder, T. H. Osborne, K. H. Burrell, R. J. Groebner, A. W. Leonard, R. Nazikian, D. M. Orlov, O. Schmitz, M. R. Wade, H. R. Wilson

Research output: Contribution to journal › Article › peer-review

159 Scopus citations

Abstract

The EPED model predicts the H-mode pedestal height and width based upon two fundamental and calculable constraints: (1) onset of non-local peeling-ballooning modes at low to intermediate mode number, (2) onset of nearly local kinetic ballooning modes at high mode number. We present detailed tests of the EPED model in discharges with edge localized modes (ELMs), employing new high resolution measurements, and finding good quantitative agreement across a range of parameters. The EPED model is then applied for the first time to quiescent H-mode (QH), finding a similar level of agreement between predicted and observed pedestal height and width, and suggesting that the model can be used to predict the critical density for QH-mode operation. Finally, the model is applied toward understanding the suppression of ELMs with 3D resonant magnetic perturbations (RMP). Combining EPED with plasma response physics, a new working model for RMP ELM suppression is developed. We propose that ELMs are suppressed when a "wall" associated with the RMP blocks the inward penetration of the edge transport barrier. A calculation of the required location of this "wall" with EPED is consistent with observed profile changes during RMP ELM suppression and offers an explanation for the observed dependence on safety factor (q 95).

Original language	English
Article number	056115
Journal	Physics of Plasmas
Volume	19
Issue number	5
DOIs	https://doi.org/10.1063/1.3699623
State	Published - May 2012
Externally published	Yes

Funding

This work was supported in part by the US Department of Energy under DE-FG02-95ER54309, DE-FC02-06ER54873, DE-AC02-09CH11466, DE-FG02-07ER54917, DE-FC02-04ER54698, and in part by the UK EPSCR and Euratom. The authors gratefully acknowledge contributions from the DIII-D team, in particular, the Thomson scattering group, including B. D. Bray and D. Eldon, the ELM Control by 3D Fields Task Force, and the Alternative Techniques for ELM Control group.

Funders	Funder number
EPSCR
U.S. Department of Energy	DE-AC02-09CH11466, DE-FC02-04ER54698, DE-FC02-06ER54873, DE-FG02-07ER54917, DE-FG02-95ER54309
H2020 Euratom
Engineering and Physical Sciences Research Council	EP/I500987/1, EP/D065399/1

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1063/1.3699623

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Snyder, P. B., Osborne, T. H., Burrell, K. H., Groebner, R. J., Leonard, A. W., Nazikian, R., Orlov, D. M., Schmitz, O., Wade, M. R., & Wilson, H. R. (2012). The EPED pedestal model and edge localized mode-suppressed regimes: Studies of quiescent H-mode and development of a model for edge localized mode suppression via resonant magnetic perturbations. Physics of Plasmas, 19(5), Article 056115. https://doi.org/10.1063/1.3699623

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title = "The EPED pedestal model and edge localized mode-suppressed regimes: Studies of quiescent H-mode and development of a model for edge localized mode suppression via resonant magnetic perturbations",

abstract = "The EPED model predicts the H-mode pedestal height and width based upon two fundamental and calculable constraints: (1) onset of non-local peeling-ballooning modes at low to intermediate mode number, (2) onset of nearly local kinetic ballooning modes at high mode number. We present detailed tests of the EPED model in discharges with edge localized modes (ELMs), employing new high resolution measurements, and finding good quantitative agreement across a range of parameters. The EPED model is then applied for the first time to quiescent H-mode (QH), finding a similar level of agreement between predicted and observed pedestal height and width, and suggesting that the model can be used to predict the critical density for QH-mode operation. Finally, the model is applied toward understanding the suppression of ELMs with 3D resonant magnetic perturbations (RMP). Combining EPED with plasma response physics, a new working model for RMP ELM suppression is developed. We propose that ELMs are suppressed when a {"}wall{"} associated with the RMP blocks the inward penetration of the edge transport barrier. A calculation of the required location of this {"}wall{"} with EPED is consistent with observed profile changes during RMP ELM suppression and offers an explanation for the observed dependence on safety factor (q 95).",

author = "Snyder, {P. B.} and Osborne, {T. H.} and Burrell, {K. H.} and Groebner, {R. J.} and Leonard, {A. W.} and R. Nazikian and Orlov, {D. M.} and O. Schmitz and Wade, {M. R.} and Wilson, {H. R.}",

year = "2012",

month = may,

doi = "10.1063/1.3699623",

language = "English",

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journal = "Physics of Plasmas",

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Snyder, PB, Osborne, TH, Burrell, KH, Groebner, RJ, Leonard, AW, Nazikian, R, Orlov, DM, Schmitz, O, Wade, MR & Wilson, HR 2012, 'The EPED pedestal model and edge localized mode-suppressed regimes: Studies of quiescent H-mode and development of a model for edge localized mode suppression via resonant magnetic perturbations', Physics of Plasmas, vol. 19, no. 5, 056115. https://doi.org/10.1063/1.3699623

The EPED pedestal model and edge localized mode-suppressed regimes: Studies of quiescent H-mode and development of a model for edge localized mode suppression via resonant magnetic perturbations. / Snyder, P. B.; Osborne, T. H.; Burrell, K. H. et al.
In: Physics of Plasmas, Vol. 19, No. 5, 056115, 05.2012.

Research output: Contribution to journal › Article › peer-review

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T1 - The EPED pedestal model and edge localized mode-suppressed regimes

T2 - Studies of quiescent H-mode and development of a model for edge localized mode suppression via resonant magnetic perturbations

AU - Snyder, P. B.

AU - Osborne, T. H.

AU - Burrell, K. H.

AU - Groebner, R. J.

AU - Leonard, A. W.

AU - Nazikian, R.

AU - Orlov, D. M.

AU - Schmitz, O.

AU - Wade, M. R.

AU - Wilson, H. R.

PY - 2012/5

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N2 - The EPED model predicts the H-mode pedestal height and width based upon two fundamental and calculable constraints: (1) onset of non-local peeling-ballooning modes at low to intermediate mode number, (2) onset of nearly local kinetic ballooning modes at high mode number. We present detailed tests of the EPED model in discharges with edge localized modes (ELMs), employing new high resolution measurements, and finding good quantitative agreement across a range of parameters. The EPED model is then applied for the first time to quiescent H-mode (QH), finding a similar level of agreement between predicted and observed pedestal height and width, and suggesting that the model can be used to predict the critical density for QH-mode operation. Finally, the model is applied toward understanding the suppression of ELMs with 3D resonant magnetic perturbations (RMP). Combining EPED with plasma response physics, a new working model for RMP ELM suppression is developed. We propose that ELMs are suppressed when a "wall" associated with the RMP blocks the inward penetration of the edge transport barrier. A calculation of the required location of this "wall" with EPED is consistent with observed profile changes during RMP ELM suppression and offers an explanation for the observed dependence on safety factor (q 95).

AB - The EPED model predicts the H-mode pedestal height and width based upon two fundamental and calculable constraints: (1) onset of non-local peeling-ballooning modes at low to intermediate mode number, (2) onset of nearly local kinetic ballooning modes at high mode number. We present detailed tests of the EPED model in discharges with edge localized modes (ELMs), employing new high resolution measurements, and finding good quantitative agreement across a range of parameters. The EPED model is then applied for the first time to quiescent H-mode (QH), finding a similar level of agreement between predicted and observed pedestal height and width, and suggesting that the model can be used to predict the critical density for QH-mode operation. Finally, the model is applied toward understanding the suppression of ELMs with 3D resonant magnetic perturbations (RMP). Combining EPED with plasma response physics, a new working model for RMP ELM suppression is developed. We propose that ELMs are suppressed when a "wall" associated with the RMP blocks the inward penetration of the edge transport barrier. A calculation of the required location of this "wall" with EPED is consistent with observed profile changes during RMP ELM suppression and offers an explanation for the observed dependence on safety factor (q 95).

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DO - 10.1063/1.3699623

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VL - 19

JO - Physics of Plasmas

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ER -

The EPED pedestal model and edge localized mode-suppressed regimes: Studies of quiescent H-mode and development of a model for edge localized mode suppression via resonant magnetic perturbations

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