skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Modeling of 3D magnetic equilibrium effects on edge turbulence stability during RMP ELM suppression in tokamaks

Abstract

Some recent experimental observations have found turbulent fluctuation structures that are non-axisymmetric in a tokamak with applied 3D fields. Here, two fluid resistive effects are shown to produce changes relevant to turbulent transport in the modeled 3D magnetohydrodynamic (MHD) equilibrium of tokamak pedestals with these 3D fields applied. Ideal MHD models are insufficient to reproduce the relevant effects. By calculating the ideal 3D equilibrium using the VMEC code, the geometric shaping parameters that determine linear turbulence stability, including the normal curvature and local magnetic shear, are shown to be only weakly modified by applied 3D fields in the DIII-D tokamak. These ideal MHD effects are therefore not sufficient to explain the observed changes to fluctuations and transport. Using the M3D-C1 code to model the 3D equilibrium, density is shown to be redistributed on flux surfaces in the pedestal when resistive two fluid effects are included, while islands are screened by rotation in this region. Furthermore, the redistribution of density results in density and pressure gradient scale lengths that vary within pedestal flux surfaces between different helically localized flux tubes. This would produce different drive terms for trapped electron mode and kinetic ballooning mode turbulence, the latter of which is expectedmore » to be the limiting factor for pedestal pressure gradients in DIII-D.« less

Authors:
ORCiD logo [1];  [1];  [1];  [2];  [1];  [3];  [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  3. General Atomics, San Diego, CA (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); General Atomics, San Diego, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
OSTI Identifier:
1376604
Alternate Identifier(s):
OSTI ID: 1374600
Grant/Contract Number:  
AC05-00OR22725; AC02-09CH11466; FC02-04ER54698
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 57; Journal Issue: 11; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; RMP; equilibrium; turbulence

Citation Formats

Wilcox, R. S., Wingen, A., Cianciosa, M. R., Ferraro, N. M., Hirshman, S. P., Paz-Soldan, C., Seal, S. K., Shafer, M. W., and Unterberg, E. A. Modeling of 3D magnetic equilibrium effects on edge turbulence stability during RMP ELM suppression in tokamaks. United States: N. p., 2017. Web. doi:10.1088/1741-4326/aa7bad.
Wilcox, R. S., Wingen, A., Cianciosa, M. R., Ferraro, N. M., Hirshman, S. P., Paz-Soldan, C., Seal, S. K., Shafer, M. W., & Unterberg, E. A. Modeling of 3D magnetic equilibrium effects on edge turbulence stability during RMP ELM suppression in tokamaks. United States. doi:10.1088/1741-4326/aa7bad.
Wilcox, R. S., Wingen, A., Cianciosa, M. R., Ferraro, N. M., Hirshman, S. P., Paz-Soldan, C., Seal, S. K., Shafer, M. W., and Unterberg, E. A. Fri . "Modeling of 3D magnetic equilibrium effects on edge turbulence stability during RMP ELM suppression in tokamaks". United States. doi:10.1088/1741-4326/aa7bad. https://www.osti.gov/servlets/purl/1376604.
@article{osti_1376604,
title = {Modeling of 3D magnetic equilibrium effects on edge turbulence stability during RMP ELM suppression in tokamaks},
author = {Wilcox, R. S. and Wingen, A. and Cianciosa, M. R. and Ferraro, N. M. and Hirshman, S. P. and Paz-Soldan, C. and Seal, S. K. and Shafer, M. W. and Unterberg, E. A.},
abstractNote = {Some recent experimental observations have found turbulent fluctuation structures that are non-axisymmetric in a tokamak with applied 3D fields. Here, two fluid resistive effects are shown to produce changes relevant to turbulent transport in the modeled 3D magnetohydrodynamic (MHD) equilibrium of tokamak pedestals with these 3D fields applied. Ideal MHD models are insufficient to reproduce the relevant effects. By calculating the ideal 3D equilibrium using the VMEC code, the geometric shaping parameters that determine linear turbulence stability, including the normal curvature and local magnetic shear, are shown to be only weakly modified by applied 3D fields in the DIII-D tokamak. These ideal MHD effects are therefore not sufficient to explain the observed changes to fluctuations and transport. Using the M3D-C1 code to model the 3D equilibrium, density is shown to be redistributed on flux surfaces in the pedestal when resistive two fluid effects are included, while islands are screened by rotation in this region. Furthermore, the redistribution of density results in density and pressure gradient scale lengths that vary within pedestal flux surfaces between different helically localized flux tubes. This would produce different drive terms for trapped electron mode and kinetic ballooning mode turbulence, the latter of which is expected to be the limiting factor for pedestal pressure gradients in DIII-D.},
doi = {10.1088/1741-4326/aa7bad},
journal = {Nuclear Fusion},
issn = {0029-5515},
number = 11,
volume = 57,
place = {United States},
year = {2017},
month = {7}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 4 works
Citation information provided by
Web of Science

Save / Share: