Title: Energy transport analysis of NSTX plasmas with the TGLF turbulent and NEO neoclassical transport models

Abstract

This work presents a study of plasma transport at low aspect ratio on the National Spherical Torus Experiment tokamak, where the turbulent and neoclassical energy fluxes calculated by the quasilinear Trapped Gyro Landau Fluid (TGLF) model and the multi species drift-kinetic Neoclassical solver (NEO) are validated against experimental data. The turbulent energy transport of two plasma discharges, one in the L-mode confinement regime and another in the H-mode regime, is dominated by electrostatic drift-wave instabilities, while the ion heat transport has a significant neoclassical contribution. The data analysis workflow is described in detail to understand how the variations of mapping and fitting of experimental data affect the power balance solution and subsequent flux-matching plasma profile predictions with the TGYRO solver. On average, the predicted plasma profiles are consistent with experimental data. However, the solutions are sensitive to various input parameters, including boundary conditions, and the electron-ion coupling. Linear gyrokinetic stability analysis demonstrates close agreement of the real frequencies of unstable modes between TGLF and CGYRO gyrokinetic simulations, but higher growth rates are predicted by TGLF, especially for the H-mode case. Estimates of the low-k modes' contributions to the total flux are consistent with linear stability analysis and the E × B suppression of turbulence in TGLF simulations with the SAT1 saturation model, while the SAT2 saturation model over-predicts the low-k modes' contribution in the H-mode case. Moreover, the results with SAT1 model are consistent with power balance analysis, which indicates only neoclassical ion energy fluxes inside ρ < 0.4 in the L-mode case and $$\rho \unicode{x2A7D} 0.7$$ in the H-mode case. The presence of multi-scale turbulence and ion-scale driven zonal flow mixing effects are also observed in TGLF scans of the electron turbulent heat flux over a range of temperature gradients and the electron-ion temperature ratio, which could explain the strong model sensitivity to variations of input parameters.

Authors:

Avdeeva, G.  ^[1];

• Search DOE PAGES for author "Avdeeva, G."
• Search DOE PAGES for ORCID "0000-0001-7072-7967"

Thome, K. E.  ^[2];

• Search DOE PAGES for author "Thome, K. E."
• Search DOE PAGES for ORCID "0000-0002-4801-3922"

Smith, S. P.  ^[2];

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Battaglia, D. J.  ^[3];

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• Search DOE PAGES for ORCID "0000-0001-8897-9740"

Clauser, C. F.  ^[4];

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• Search DOE PAGES for ORCID "0000-0002-2597-5061"

Guttenfelder, W.  ^[5];

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• Search DOE PAGES for ORCID "0000-0001-8181-058X"

Kaye, S. M.  ^[5];

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• Search DOE PAGES for ORCID "0000-0002-2514-1163"

McClenaghan, J. ^[2]; Meneghini, O.  ^[2];

• Search DOE PAGES for author "Meneghini, O."
• Search DOE PAGES for ORCID "0000-0001-5100-5483"

Odstrcil, T.  ^[2];

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• Search DOE PAGES for ORCID "0000-0003-4173-4230"

Staebler, G.  ^[2]

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• Search DOE PAGES for ORCID "0000-0002-1944-1733"

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+ Show Author Affiliations

1. Oak Ridge Associated Universities (ORAU), Oak Ridge, TN (United States); General Atomics, San Diego, CA (United States)
2. General Atomics, San Diego, CA (United States)
3. Commonwealth Fusion Systems, Bethlehem, PA (United States)
4. Lehigh University, Bethlehem, PA (United States)
5. Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Publication Date:

Wed Oct 04 00:00:00 EDT 2023

Research Org.:

General Atomics, San Diego, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Fusion Energy Sciences (FES)

OSTI Identifier:

2202249

Grant/Contract Number:  

SC0021113; AC02-09CH11466

Resource Type:

Accepted Manuscript

Journal Name:

Nuclear Fusion

Additional Journal Information:

Journal Volume: 63; Journal Issue: 12; Journal ID: ISSN 0029-5515

Publisher:

IOP Science

Country of Publication:

United States

Language:

English

Subject:

70 PLASMA PHYSICS AND FUSION TECHNOLOGY; NSTX; TGLF; NEO; energy transport analysis; electrostatic drift-wave instabilities