Novel intrinsic helical cores and MHD dynamo flux pumping evidence in DIII-D

W. Boyes; F. Turco; J. Hanson; G. A. Navratil; A. Turnbull; A. Hyatt; T. Luce; W. Meyer; A. O. Nelson; T. Odstrcil; T. Osborne; F. Scotti; A. Welander; A. Wingen

doi:10.1088/1741-4326/ad89d9

Novel intrinsic helical cores and MHD dynamo flux pumping evidence in DIII-D

W. Boyes, F. Turco, J. Hanson, G. A. Navratil, A. Turnbull, A. Hyatt, T. Luce, W. Meyer, A. O. Nelson, T. Odstrcil, T. Osborne, F. Scotti, A. Welander, A. Wingen

Advanced Tokamak Physics

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

Abstract

Evidence of a MHD dynamo brought about by intrinsic helical core structures in negative triangularity (NT) and ITER baseline scenario (IBS) plasmas demonstrates paths to operating tokamaks without seeds for deleterious global MHD modes. A stationary sawtooth- and edge localized mode-free state maintains high performance for long durations in a strong NT shape in the DIII-D tokamak. Disparity between minimum safety factor values predicted by magnetic flux diffusion theory and derived from experiment suggests anomalous flux diffusion by an MHD dynamo, driven by flows associated with quasi-interchange modes. Stability calculations with the GATO code find NT and IBS experimental equilibria unstable to quasi-interchange modes, in agreement with observed saturated activity. IBS discharges with similar magnetic winding structure occupy robust helical core states following a transition from sawtooth instabilities. These states agree with prior modeling of helical core bifurcation thresholds with the VMEC equilibrium code.

Original language	English
Article number	124005
Journal	Nuclear Fusion
Volume	64
Issue number	12
DOIs	https://doi.org/10.1088/1741-4326/ad89d9
State	Published - Dec 2024

Funding

This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences, using the DIII-D National Fusion Facility, a DOE Office of Science user facility, under Award(s) FG02-04ER54761, DE-FC02-04ER54698, DE-AC05-00OR22725, DE-AC52-07NA27344, DE-SC0022270, and DE-SC0022272.

Funders	Funder number
U.S. Department of Energy
Fusion Energy Sciences
Office of Science	DE-AC05-00OR22725, DE-SC0022272, DE-FC02-04ER54698, FG02-04ER54761, DE-SC0022270, DE-AC52-07NA27344
Office of Science

Keywords

flux pumping
ITER baseline scenario
magnetohydrodynamics
negative triangularity
reactor scenario development

UN SDGs

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

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10.1088/1741-4326/ad89d9

Cite this

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title = "Novel intrinsic helical cores and MHD dynamo flux pumping evidence in DIII-D",

abstract = "Evidence of a MHD dynamo brought about by intrinsic helical core structures in negative triangularity (NT) and ITER baseline scenario (IBS) plasmas demonstrates paths to operating tokamaks without seeds for deleterious global MHD modes. A stationary sawtooth- and edge localized mode-free state maintains high performance for long durations in a strong NT shape in the DIII-D tokamak. Disparity between minimum safety factor values predicted by magnetic flux diffusion theory and derived from experiment suggests anomalous flux diffusion by an MHD dynamo, driven by flows associated with quasi-interchange modes. Stability calculations with the GATO code find NT and IBS experimental equilibria unstable to quasi-interchange modes, in agreement with observed saturated activity. IBS discharges with similar magnetic winding structure occupy robust helical core states following a transition from sawtooth instabilities. These states agree with prior modeling of helical core bifurcation thresholds with the VMEC equilibrium code.",

keywords = "flux pumping, ITER baseline scenario, magnetohydrodynamics, negative triangularity, reactor scenario development",

author = "W. Boyes and F. Turco and J. Hanson and Navratil, {G. A.} and A. Turnbull and A. Hyatt and T. Luce and W. Meyer and Nelson, {A. O.} and T. Odstrcil and T. Osborne and F. Scotti and A. Welander and A. Wingen",

note = "Publisher Copyright: {\textcopyright} 2024 The Author(s). Published by IOP Publishing Ltd on behalf of the IAEA.",

year = "2024",

month = dec,

doi = "10.1088/1741-4326/ad89d9",

language = "English",

volume = "64",

journal = "Nuclear Fusion",

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T1 - Novel intrinsic helical cores and MHD dynamo flux pumping evidence in DIII-D

AU - Boyes, W.

AU - Turco, F.

AU - Hanson, J.

AU - Navratil, G. A.

AU - Turnbull, A.

AU - Hyatt, A.

AU - Luce, T.

AU - Meyer, W.

AU - Nelson, A. O.

AU - Odstrcil, T.

AU - Osborne, T.

AU - Scotti, F.

AU - Welander, A.

AU - Wingen, A.

PY - 2024/12

Y1 - 2024/12

N2 - Evidence of a MHD dynamo brought about by intrinsic helical core structures in negative triangularity (NT) and ITER baseline scenario (IBS) plasmas demonstrates paths to operating tokamaks without seeds for deleterious global MHD modes. A stationary sawtooth- and edge localized mode-free state maintains high performance for long durations in a strong NT shape in the DIII-D tokamak. Disparity between minimum safety factor values predicted by magnetic flux diffusion theory and derived from experiment suggests anomalous flux diffusion by an MHD dynamo, driven by flows associated with quasi-interchange modes. Stability calculations with the GATO code find NT and IBS experimental equilibria unstable to quasi-interchange modes, in agreement with observed saturated activity. IBS discharges with similar magnetic winding structure occupy robust helical core states following a transition from sawtooth instabilities. These states agree with prior modeling of helical core bifurcation thresholds with the VMEC equilibrium code.

AB - Evidence of a MHD dynamo brought about by intrinsic helical core structures in negative triangularity (NT) and ITER baseline scenario (IBS) plasmas demonstrates paths to operating tokamaks without seeds for deleterious global MHD modes. A stationary sawtooth- and edge localized mode-free state maintains high performance for long durations in a strong NT shape in the DIII-D tokamak. Disparity between minimum safety factor values predicted by magnetic flux diffusion theory and derived from experiment suggests anomalous flux diffusion by an MHD dynamo, driven by flows associated with quasi-interchange modes. Stability calculations with the GATO code find NT and IBS experimental equilibria unstable to quasi-interchange modes, in agreement with observed saturated activity. IBS discharges with similar magnetic winding structure occupy robust helical core states following a transition from sawtooth instabilities. These states agree with prior modeling of helical core bifurcation thresholds with the VMEC equilibrium code.

KW - flux pumping

KW - ITER baseline scenario

KW - magnetohydrodynamics

KW - negative triangularity

KW - reactor scenario development

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DO - 10.1088/1741-4326/ad89d9

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SN - 0029-5515

VL - 64

JO - Nuclear Fusion

JF - Nuclear Fusion

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ER -

Novel intrinsic helical cores and MHD dynamo flux pumping evidence in DIII-D

Abstract

Funding

Keywords

UN SDGs

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