Progress in Simulating Turbulent Electron Thermal Transport in NSTX
Abstract
Nonlinear simulations based on multiple NSTX discharge scenarios have progressed to help differentiate unique instability mechanisms and to validate with experimental turbulence and transport data. First nonlinear gyrokinetic simulations of microtearing (MT) turbulence in a high-beta NSTX H-mode discharge predict experimental levels of electron thermal transport that are dominated by magnetic flutter and increase with collisionality, roughly consistent with energy confinement times in dimensionless collisionality scaling experiments. Electron temperature gradient (ETG) simulations predict significant electron thermal transport in some low and high beta discharges when ion scales are suppressed by E x B shear. Although the predicted transport in H-modes is insensitive to variation in collisionality (inconsistent with confinement scaling), it is sensitive to variations in other parameters, particularly density gradient stabilization. In reversed shear (RS) Lmode discharges that exhibit electron internal transport barriers, ETG transport has also been shown to be suppressed nonlinearly by strong negative magnetic shear, s<<0. In many high beta plasmas, instabilities which exhibit a stiff beta dependence characteristic of kinetic ballooning modes (KBM) are sometimes found in the core region. However, they do not have a distinct finite beta threshold, instead transitioning gradually to a trapped electron mode (TEM) as beta is reduced to zero.more »
- Authors:
-
- Princeton Plasma Physics Lab., Princeton, NJ (United States)
- Lawrence Livermore National Lab., Livermore, CA (United States)
- General Atomics, San Diego, CA (United States)
- Nova Photonics, Princeton, NJ (United States)
- Publication Date:
- Research Org.:
- Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC)
- OSTI Identifier:
- 1087711
- Report Number(s):
- PPPL-4933
- DOE Contract Number:
- DE-ACO2-09CH11466
- Resource Type:
- Technical Report
- Resource Relation:
- Related Information: Nuclear Fusion
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Tokamaks, NSTX, Turbulence
Citation Formats
Guttenfelder, Walter, Kaye, S. M., Ren, Y., Bell, R. E., Hammett, G. W., LeBlanc, B. P., Mikkelsen, D. R., Peterson, J. L., Nevins, W. M., Candy, J., and Yuh, H. Progress in Simulating Turbulent Electron Thermal Transport in NSTX. United States: N. p., 2013.
Web. doi:10.2172/1087711.
Guttenfelder, Walter, Kaye, S. M., Ren, Y., Bell, R. E., Hammett, G. W., LeBlanc, B. P., Mikkelsen, D. R., Peterson, J. L., Nevins, W. M., Candy, J., & Yuh, H. Progress in Simulating Turbulent Electron Thermal Transport in NSTX. United States. doi:10.2172/1087711.
Guttenfelder, Walter, Kaye, S. M., Ren, Y., Bell, R. E., Hammett, G. W., LeBlanc, B. P., Mikkelsen, D. R., Peterson, J. L., Nevins, W. M., Candy, J., and Yuh, H. Wed .
"Progress in Simulating Turbulent Electron Thermal Transport in NSTX". United States.
doi:10.2172/1087711. https://www.osti.gov/servlets/purl/1087711.
@article{osti_1087711,
title = {Progress in Simulating Turbulent Electron Thermal Transport in NSTX},
author = {Guttenfelder, Walter and Kaye, S. M. and Ren, Y. and Bell, R. E. and Hammett, G. W. and LeBlanc, B. P. and Mikkelsen, D. R. and Peterson, J. L. and Nevins, W. M. and Candy, J. and Yuh, H.},
abstractNote = {Nonlinear simulations based on multiple NSTX discharge scenarios have progressed to help differentiate unique instability mechanisms and to validate with experimental turbulence and transport data. First nonlinear gyrokinetic simulations of microtearing (MT) turbulence in a high-beta NSTX H-mode discharge predict experimental levels of electron thermal transport that are dominated by magnetic flutter and increase with collisionality, roughly consistent with energy confinement times in dimensionless collisionality scaling experiments. Electron temperature gradient (ETG) simulations predict significant electron thermal transport in some low and high beta discharges when ion scales are suppressed by E x B shear. Although the predicted transport in H-modes is insensitive to variation in collisionality (inconsistent with confinement scaling), it is sensitive to variations in other parameters, particularly density gradient stabilization. In reversed shear (RS) Lmode discharges that exhibit electron internal transport barriers, ETG transport has also been shown to be suppressed nonlinearly by strong negative magnetic shear, s<<0. In many high beta plasmas, instabilities which exhibit a stiff beta dependence characteristic of kinetic ballooning modes (KBM) are sometimes found in the core region. However, they do not have a distinct finite beta threshold, instead transitioning gradually to a trapped electron mode (TEM) as beta is reduced to zero. Nonlinear simulations of this "hybrid" TEM/KBM predict significant transport in all channels, with substantial contributions from compressional magnetic perturbations. As multiple instabilities are often unstable simultaneously in the same plasma discharge, even on the same flux surface, unique parametric dependencies are discussed which may be useful for distinguishing the different mechanisms experimentally.},
doi = {10.2172/1087711},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jul 17 00:00:00 EDT 2013},
month = {Wed Jul 17 00:00:00 EDT 2013}
}
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