Disruptive neoclassical tearing mode seeding in DIII-D with implications for ITER

R. J. La Haye; C. Chrystal; E. J. Strait; J. D. Callen; C. C. Hegna; E. C. Howell; M. Okabayashi; R. S. Wilcox

doi:10.1088/1741-4326/ac351f

Disruptive neoclassical tearing mode seeding in DIII-D with implications for ITER

R. J. La Haye, C. Chrystal, E. J. Strait, J. D. Callen, C. C. Hegna, E. C. Howell, M. Okabayashi, R. S. Wilcox

Advanced Tokamak Physics

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

20 Scopus citations

Abstract

New studies identify the critical parameters and physics governing disruptive neoclassical tearing mode (NTM) onset. An m/n = 2/1 mode in DIII-D that begins to grow robustly after a seeding event (edge localized mode ELM or sawtooth precursor and crash) causes the mode rotation to drop close to the plasma's E r = 0 rest frame; this condition opens the stabilizing ion-polarization current 'gate' and destabilizes an otherwise marginally stable NTM. Our new experimental and theoretical insights and novel toroidal theory-based modeling are benchmarked and scalable to ITER and other future experiments. The nominal ITER rotation at q = 2 is found to be stabilizing ('gate closed') except for MHD-induced transients that could 'open the gate'. Extrapolating from the DIII-D ITER baseline scenario (IBS) discharges, MHD transients are much more likely to destabilize problematic robustly growing 2/1 NTMs in ITER; this makes predictions of seeding and control of both ELMs and sawteeth imperative for more than just minimizing divertor pulsed-heat loading.

Original language	English
Article number	056017
Journal	Nuclear Fusion
Volume	62
Issue number	5
DOIs	https://doi.org/10.1088/1741-4326/ac351f
State	Published - May 2022

Funding

This material is based upon work supported by the US 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) DE-FC02-04ER54698, DE-FG02-86ER53218, DE-AC05-00OR22725, DE-AC02-09CH11466 and DE-SC0018313. N.Z. Taylor is thanked for leading the session on DIII-D to get fast CER data. Z.R. Wang is thanked for the Resistive DCON tearing stability code analysis. A.R. Polevoi is thanked for help in getting the ITER parameters.

Funders	Funder number
U.S. Department of Energy
Office of Science	DE-AC05-00OR22725, DE-FG02-86ER53218, DE-AC02-09CH11466, DE-FC02-04ER54698, DE-SC0018313
Fusion Energy Sciences

Keywords

stability
tearing
tokamak

UN SDGs

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

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abstract = "New studies identify the critical parameters and physics governing disruptive neoclassical tearing mode (NTM) onset. An m/n = 2/1 mode in DIII-D that begins to grow robustly after a seeding event (edge localized mode ELM or sawtooth precursor and crash) causes the mode rotation to drop close to the plasma's E r = 0 rest frame; this condition opens the stabilizing ion-polarization current 'gate' and destabilizes an otherwise marginally stable NTM. Our new experimental and theoretical insights and novel toroidal theory-based modeling are benchmarked and scalable to ITER and other future experiments. The nominal ITER rotation at q = 2 is found to be stabilizing ('gate closed') except for MHD-induced transients that could 'open the gate'. Extrapolating from the DIII-D ITER baseline scenario (IBS) discharges, MHD transients are much more likely to destabilize problematic robustly growing 2/1 NTMs in ITER; this makes predictions of seeding and control of both ELMs and sawteeth imperative for more than just minimizing divertor pulsed-heat loading.",

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AU - Wilcox, R. S.

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Disruptive neoclassical tearing mode seeding in DIII-D with implications for ITER

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Keywords

UN SDGs

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