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Title: Ion temperature gradient turbulence modification in quasi-axisymmetry

Abstract

The large flexibility of the proposed QUASAR facility is leveraged in order to explore the effect of magnetic shear on adiabatic Ion Temperature Gradient (ITG) turbulence. The QUASAR facility is a reimagining of the National Compact Stellarator Experiment utilizing and expanding upon the already constructed coil set. Recent work using fixed boundary optimization of the LI383 equilibrium (upon which QUASAR is based) has suggested possible improvements to ITG turbulence. In this work, a different approach is taken, wherein a series of self-consistent free boundary VMEC equilibria are developed for QUASAR. These equilibria assume temperature and density profiles consistent with 2% beta and ohmic current drive. In each configuration, the toroidal field coils are energized to different values and the STELLOPT code is used to vary the modular coil current and net toroidal current. The edge value of rotational transform is targeted in the optimization, producing a magnetic shear scan. All these configurations share similar neoclassical transport levels, while nonlinear GENE flux tube simulations show up to a factor of four change in adiabatic ITG turbulence at various radii. Comparisons of proxy functions and linear flux tube runs are also made. This work highlights the capability of the QUASAR experiment asmore » a tool to explore transport in 3D magnetic fields and the possibility of the further improvements to stellarators through optimization.« less

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [1]; ORCiD logo [1]
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  2. Max-Planck Institut-für-Plasmaphysik, Greifswald (Germany)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1511480
Grant/Contract Number:  
AC02-09CH11466
Resource Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 26; Journal Issue: 2; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Lazerson, Samuel A., Xanthopoulos, Pavlos, Mynick, Harry, and Gates, David. Ion temperature gradient turbulence modification in quasi-axisymmetry. United States: N. p., 2019. Web. doi:10.1063/1.5084116.
Lazerson, Samuel A., Xanthopoulos, Pavlos, Mynick, Harry, & Gates, David. Ion temperature gradient turbulence modification in quasi-axisymmetry. United States. doi:10.1063/1.5084116.
Lazerson, Samuel A., Xanthopoulos, Pavlos, Mynick, Harry, and Gates, David. Fri . "Ion temperature gradient turbulence modification in quasi-axisymmetry". United States. doi:10.1063/1.5084116.
@article{osti_1511480,
title = {Ion temperature gradient turbulence modification in quasi-axisymmetry},
author = {Lazerson, Samuel A. and Xanthopoulos, Pavlos and Mynick, Harry and Gates, David},
abstractNote = {The large flexibility of the proposed QUASAR facility is leveraged in order to explore the effect of magnetic shear on adiabatic Ion Temperature Gradient (ITG) turbulence. The QUASAR facility is a reimagining of the National Compact Stellarator Experiment utilizing and expanding upon the already constructed coil set. Recent work using fixed boundary optimization of the LI383 equilibrium (upon which QUASAR is based) has suggested possible improvements to ITG turbulence. In this work, a different approach is taken, wherein a series of self-consistent free boundary VMEC equilibria are developed for QUASAR. These equilibria assume temperature and density profiles consistent with 2% beta and ohmic current drive. In each configuration, the toroidal field coils are energized to different values and the STELLOPT code is used to vary the modular coil current and net toroidal current. The edge value of rotational transform is targeted in the optimization, producing a magnetic shear scan. All these configurations share similar neoclassical transport levels, while nonlinear GENE flux tube simulations show up to a factor of four change in adiabatic ITG turbulence at various radii. Comparisons of proxy functions and linear flux tube runs are also made. This work highlights the capability of the QUASAR experiment as a tool to explore transport in 3D magnetic fields and the possibility of the further improvements to stellarators through optimization.},
doi = {10.1063/1.5084116},
journal = {Physics of Plasmas},
number = 2,
volume = 26,
place = {United States},
year = {2019},
month = {2}
}

Journal Article:
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This content will become publicly available on February 15, 2020
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