Importance of $\delta B_{\|}$ on ETG stability, turbulence, and transport in NSTX

Li, P.-Y.; Hatch, D. R.; Parisi, J. F.; Lampert, M.; Belli, E. A.; Kotschenreuther, M.; Mahajan, S. M.

doi:10.1088/1741-4326/ae06b3

Importance of $$\delta B_{\|}$$ on ETG stability, turbulence, and transport in NSTX

Journal Article · Fri Sep 26 00:00:00 EDT 2025 · Nuclear Fusion

DOI:https://doi.org/10.1088/1741-4326/ae06b3· OSTI ID:2997870

^[1]; ^[2]; ^[3]; ^[3]; ^[4]; Kotschenreuther, M. ^[5]; Mahajan, S. M. ^[2]

Univ. of Texas, Austin, TX (United States)
Univ. of Texas, Austin, TX (United States); ExoFusion, Austin, TX (United States)
Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
General Atomics, San Diego, CA (United States)
ExoFusion, Austin, TX (United States)

This study employs electron-scale gyrokinetic simulations to investigate the electron temperature gradient (ETG) driven instabilities, turbulence, and transport in the pedestal region of the National Spherical Torus Experiment, comparing non-lithiated (narrow pedestal) and lithiated (wide pedestal) scenarios. Our findings reveal that, in the non-lithiated case, a branch of strongly unstable ETG modes exhibiting finite parallel magnetic field fluctuations ($$\delta B_{\parallel} \neq 0$$) emerges at the pedestal top and upper density pedestal region. This branch is uncovered only when $$\delta B_{\parallel}$$ is retained in the simulations and is associated with substantial electrostatic electron heat flux. This region of strong ETG transport corresponds to the only region in the plasma where the pressure gradient is far below the critical gradient for kinetic ballooning modes. We investigated the origin of this finite $$\delta B_{\parallel}$$ ETG branch by analyzing the gyrokinetic field equations. Nonlinear saturation is also analyzed and contrasted for simulations with and without $$\delta B_{\parallel}$$. In contrast with the nonlithiated case, ETG modes in the lithiated case produce substantial transport in the steep gradient region, but are negligible at the pedestal top.

View Accepted Manuscript (DOE)

Research Organization:: Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States); Univ. of Texas, Austin, TX (United States)

Sponsoring Organization:: USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES)

Grant/Contract Number:: AC02-09CH11466; FG02-04ER54742; SC0022115

OSTI ID:: 2997870

Alternate ID(s):: OSTI ID: 2997976
OSTI ID: 2997868

Report Number(s):: SC0022115

Journal Information:: Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 10 Vol. 65; ISSN 0029-5515; ISSN 1741-4326

Publisher:: IOP PublishingCopyright Statement

Country of Publication:: United States

Language:: English

References (48)

Massively parallel Vlasov simulation of electromagnetic drift-wave turbulence Jenko, Frank Computer Physics Communications, Vol. 125, Issue 1-3 https://doi.org/10.1016/S0010-4655(99)00489-0	journal	March 2000
A high-accuracy Eulerian gyrokinetic solver for collisional plasmas Candy, J.; Belli, E. A.; Bravenec, R. V. Journal of Computational Physics, Vol. 324 https://doi.org/10.1016/j.jcp.2016.07.039	journal	November 2016
Stabilizing impact of high gradient of β on microturbulence Bourdelle, C.; Dorland, W.; Garbet, X. Physics of Plasmas, Vol. 10, Issue 7 https://doi.org/10.1063/1.1585032	journal	July 2003
The effect of lithium surface coatings on plasma performance in the National Spherical Torus Experiment Kugel, H. W.; Bell, M. G.; Ahn, J. -W. Physics of Plasmas, Vol. 15, Issue 5 https://doi.org/10.1063/1.2906260	journal	May 2008
Gyrokinetic turbulence under near-separatrix or nonaxisymmetric conditions Jenko, F.; Told, D.; Xanthopoulos, P. Physics of Plasmas, Vol. 16, Issue 5 https://doi.org/10.1063/1.3089603	journal	May 2009
Gyrokinetic simulations of magnetic reconnection Pueschel, M. J.; Jenko, F.; Told, D. Physics of Plasmas, Vol. 18, Issue 11 https://doi.org/10.1063/1.3656965	journal	November 2011
Correlations between quasi-coherent fluctuations and the pedestal evolution during the inter-edge localized modes phase on DIII-Da) Diallo, A.; Groebner, R. J.; Rhodes, T. L. Physics of Plasmas, Vol. 22, Issue 5 https://doi.org/10.1063/1.4921148	journal	May 2015
Particle-in-cell δf gyrokinetic simulations of the microtearing mode Chowdhury, J.; Chen, Yang; Wan, Weigang Physics of Plasmas, Vol. 23, Issue 1 https://doi.org/10.1063/1.4940333	journal	January 2016
Nonlinear gyrokinetic equations for low-frequency electromagnetic waves in general plasma equilibria Frieman, E. A. Physics of Fluids, Vol. 25, Issue 3 https://doi.org/10.1063/1.863762	journal	January 1982
Ion temperature gradient turbulence simulations and plasma flux surface shape Waltz, R. E.; Miller, R. L. Physics of Plasmas, Vol. 6, Issue 11 https://doi.org/10.1063/1.873694	journal	November 1999
Electron temperature gradient driven turbulence Jenko, F.; Dorland, W.; Kotschenreuther, M. Physics of Plasmas, Vol. 7, Issue 5 https://doi.org/10.1063/1.874014	journal	May 2000
Gyrokinetic benchmark of the electron temperature-gradient instability in the pedestal region Hassan, Ehab; Hatch, D. R.; Guttenfelder, W. Physics of Plasmas, Vol. 28, Issue 6 https://doi.org/10.1063/5.0043006	journal	June 2021
Saturation physics of threshold heat-flux reduction Li, P. -Y.; Terry, P. W.; Whelan, G. G. Physics of Plasmas, Vol. 28, Issue 10 https://doi.org/10.1063/5.0059335	journal	October 2021
Assessing physics of ion temperature gradient turbulence via hierarchical reduced-model representations Li, P. -Y.; Terry, P. W. Physics of Plasmas, Vol. 29, Issue 4 https://doi.org/10.1063/5.0080511	journal	April 2022
Reduced models for ETG transport in the tokamak pedestal Hatch, D. R.; Michoski, C.; Kuang, D. Physics of Plasmas, Vol. 29, Issue 6 https://doi.org/10.1063/5.0087403	journal	June 2022
ETG turbulence in a tokamak pedestal Walker, Justin; Hatch, David R. Physics of Plasmas, Vol. 30, Issue 8 https://doi.org/10.1063/5.0146968	journal	August 2023
Kinetic-ballooning-bifurcation in tokamak pedestals across shaping and aspect-ratio Parisi, J. F.; Nelson, A. O.; Gaur, R. Physics of Plasmas, Vol. 31, Issue 3 https://doi.org/10.1063/5.0190818	journal	March 2024
Global micro-tearing modes in the wide pedestal of an NSTX plasma Dominski, J.; Guttenfelder, W.; Hatch, D. Physics of Plasmas, Vol. 31, Issue 4 https://doi.org/10.1063/5.0200894	journal	April 2024
Electron temperature gradient instability and transport analysis in NSTX and NSTX-U plasmas Clauser, C. F.; Rafiq, T.; Parisi, J. Physics of Plasmas, Vol. 32, Issue 2 https://doi.org/10.1063/5.0232697	journal	February 2025
Long-pulse hybrid scenario development in JT-60U Oyama, N.; Isayama, A.; Matsunaga, G. Nuclear Fusion, Vol. 49, Issue 6 https://doi.org/10.1088/0029-5515/49/6/065026	journal	May 2009
Comparison of small ELM characteristics and regimes in Alcator C-Mod, MAST and NSTX Maingi, R.; Hubbard, A. E.; Meyer, H. Nuclear Fusion, Vol. 51, Issue 6 https://doi.org/10.1088/0029-5515/51/6/063036	journal	May 2011
Edge microstability of NSTX plasmas without and with lithium-coated plasma-facing components Canik, J. M.; Guttenfelder, W.; Maingi, R. Nuclear Fusion, Vol. 53, Issue 11 https://doi.org/10.1088/0029-5515/53/11/113016	journal	September 2013
Gyrokinetic study of ASDEX Upgrade inter-ELM pedestal profile evolution Hatch, D. R.; Told, D.; Jenko, F. Nuclear Fusion, Vol. 55, Issue 6 https://doi.org/10.1088/0029-5515/55/6/063028	journal	May 2015
Generalized gyrokinetics Catto, P. J.; Tang, W. M.; Baldwin, D. E. Plasma Physics, Vol. 23, Issue 7 https://doi.org/10.1088/0032-1028/23/7/005	journal	July 1981
Multiscale gyrokinetics for rotating tokamak plasmas: fluctuations, transport and energy flows Abel, I. G.; Plunk, G. G.; Wang, E. Reports on Progress in Physics, Vol. 76, Issue 11 https://doi.org/10.1088/0034-4885/76/11/116201	journal	October 2013
Limitations of gyrokinetics on transport time scales Parra, Felix I.; Catto, Peter J. Plasma Physics and Controlled Fusion, Vol. 50, Issue 6 https://doi.org/10.1088/0741-3335/50/6/065014	journal	April 2008
A unified method for operator evaluation in local Grad–Shafranov plasma equilibria Candy, J. Plasma Physics and Controlled Fusion, Vol. 51, Issue 10 https://doi.org/10.1088/0741-3335/51/10/105009	journal	September 2009
Spectral treatment of gyrokinetic profile curvature Candy, J.; Belli, E. A.; Staebler, G. Plasma Physics and Controlled Fusion, Vol. 62, Issue 4 https://doi.org/10.1088/1361-6587/ab759c	journal	February 2020
A gyrokinetic perspective on the JET-ILW pedestal Hatch, D. R.; Kotschenreuther, M.; Mahajan, S. Nuclear Fusion, Vol. 57, Issue 3 https://doi.org/10.1088/1741-4326/aa51e1	journal	January 2017
Pedestal transport in H-mode plasmas for fusion gain Kotschenreuther, M.; Hatch, D. R.; Mahajan, S. Nuclear Fusion, Vol. 57, Issue 6 https://doi.org/10.1088/1741-4326/aa6416	journal	April 2017
Gyrokinetic analysis and simulation of pedestals to identify the culprits for energy losses using ‘fingerprints’ Kotschenreuther, M.; Liu, X.; Hatch, D. R. Nuclear Fusion, Vol. 59, Issue 9 https://doi.org/10.1088/1741-4326/ab1fa2	journal	July 2019
Overview of the JET preparation for deuterium–tritium operation with the ITER like-wall Joffrin, E.; Abduallev, S.; Abhangi, M. Nuclear Fusion, Vol. 59, Issue 11 https://doi.org/10.1088/1741-4326/ab2276	journal	August 2019
Direct gyrokinetic comparison of pedestal transport in JET with carbon and ITER-like walls Hatch, D. R.; Kotschenreuther, M.; Mahajan, S. M. Nuclear Fusion, Vol. 59, Issue 8 https://doi.org/10.1088/1741-4326/ab25bd	journal	July 2019
Testing predictions of electron scale turbulent pedestal transport in two DIII-D ELMy H-modes Guttenfelder, W.; Groebner, R. J.; Canik, J. M. Nuclear Fusion, Vol. 61, Issue 5 https://doi.org/10.1088/1741-4326/abecc7	journal	April 2021
Predicting the critical gradient of ITG turbulence in fusion plasmas Pueschel, M. J.; Li, P. -Y.; Terry, P. W. Nuclear Fusion, Vol. 61, Issue 5 https://doi.org/10.1088/1741-4326/abf175	journal	April 2021
NSTX-U theory, modeling and analysis results Guttenfelder, W.; Battaglia, D. J.; Belova, E. Nuclear Fusion, Vol. 62, Issue 4 https://doi.org/10.1088/1741-4326/ac5448	journal	March 2022
The role of ETG modes in JET–ILW pedestals with varying levels of power and fuelling Chapman-Oplopoiou, B.; Hatch, D. R.; Field, A. R. Nuclear Fusion, Vol. 62, Issue 8 https://doi.org/10.1088/1741-4326/ac7476	journal	June 2022
Three-dimensional inhomogeneity of electron-temperature-gradient turbulence in the edge of tokamak plasmas Parisi, J. F.; Parra, F. I.; Roach, C. M. Nuclear Fusion, Vol. 62, Issue 8 https://doi.org/10.1088/1741-4326/ac786b	journal	July 2022
On the role of mode resonances in regulating zonal-flow-moderated plasma microturbulence Li, P. -Y.; Pueschel, M. J.; Terry, P. W. Nuclear Fusion, Vol. 63, Issue 2 https://doi.org/10.1088/1741-4326/acae37	journal	January 2023
ETG turbulent transport in the Mega Ampere Spherical Tokamak (MAST) pedestal Li, P. -Y.; Hatch, D. R.; Chapman-Oplopoiou, B. Nuclear Fusion, Vol. 64, Issue 1 https://doi.org/10.1088/1741-4326/ad0ef9	journal	December 2023
Modeling electron temperature profiles in the pedestal with simple formulas for ETG transport Hatch, D. R.; Kotschenreuther, M. T.; Li, P. -Y. Nuclear Fusion, Vol. 64, Issue 6 https://doi.org/10.1088/1741-4326/ad3972	journal	April 2024
Transport Barriers in magnetized plasmas- general theory with dynamical constraints Kotschenreuther, M.; Liu, X.; Mahajan, S. M. Nuclear Fusion, Vol. 64, Issue 7 https://doi.org/10.1088/1741-4326/ad4c75	journal	June 2024
On the importance of parallel magnetic-field fluctuations for electromagnetic instabilities in STEP Kennedy, D.; Roach, C. M.; Giacomin, M. Nuclear Fusion, Vol. 64, Issue 8 https://doi.org/10.1088/1741-4326/ad58f3	journal	July 2024
Comparing pedestal structure in JET-ILW H-mode plasmas with a model for stiff ETG turbulent heat transport Field, A. R.; Chapman-Oplopoiou, B.; Connor, J. W. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol. 381, Issue 2242 https://doi.org/10.1098/rsta.2021.0228	journal	January 2023
Edge-Localized-Mode Suppression through Density-Profile Modification with Lithium-Wall Coatings in the National Spherical Torus Experiment Maingi, R.; Osborne, T. H.; LeBlanc, B. P. Physical Review Letters, Vol. 103, Issue 7 https://doi.org/10.1103/PhysRevLett.103.075001	journal	August 2009
Threshold Heat-Flux Reduction by Near-Resonant Energy Transfer Terry, P. W.; Li, P. -Y.; Pueschel, M. J. Physical Review Letters, Vol. 126, Issue 2 https://doi.org/10.1103/PhysRevLett.126.025004	journal	January 2021
Composition of electron temperature gradient driven plasma turbulence in JET-ILW tokamak plasmas Chapman-Oplopoiou, B.; Walker, J.; Hatch, D. R. Physical Review Research, Vol. 7, Issue 1 https://doi.org/10.1103/PhysRevResearch.7.L012004	journal	January 2025
Local and Fast Density Pump-out by ECRH in the LHD Makino, Ryohei; Kubo, Shin; Ido, Takeshi Plasma and Fusion Research, Vol. 8, Issue 0 https://doi.org/10.1585/pfr.8.2402115	journal	January 2013

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Importance of $$\delta B_{\|}$$ on ETG stability, turbulence, and transport in NSTX

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References (48)

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