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Title: Role of 3D neoclassical particle flux in density pump-out during ELM control by RMP in DIII-D

Abstract

The application of three-dimensional (3D) resonant magnetic perturbations, for the purpose of controlling edge localized modes (ELMs) in high confinement (H-mode) tokamak fusion operations, routinely leads to a significant reduction of the plasma density during the discharge, a phenomenon termed ‘density pump-out’. Understanding the density pump-out phenomenon due to 3D fields is a longstanding challenging issue. This work reports a self-consistent toroidal model that allows initial value simulation of the density pump-out effect. The model successfully reproduces pump-out phenomenology in DIII-D ELM suppression experiments. The radial particle flux, associated with the 3D neoclassical effects (the neoclassical toroidal viscosity, NTV), is found to play an important role in producing the observed large density pump-out. The key physics is associated with the drift kinetic Landau resonances between the toroidal precession of trapped thermal ions and electrons from one side, and the magnetic field perturbation from the other side. Such resonances, occurring near the top of the pedestal region, substantially enhances the radial particle flux associated with NTV. As a general consequence of the resonant NTV flux, larger density pump-out occurs in plasmas with lower collisionality and slower toroidal rotation.

Authors:
ORCiD logo [1]; ORCiD logo [1];  [2]; ORCiD logo [3]
  1. General Atomics, San Diego, CA (United States)
  2. Donghua University, Shanghai (China)
  3. Chinese Academy of Sciences (CAS), Hefei (China)
Publication Date:
Research Org.:
General Atomics, San Diego, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
OSTI Identifier:
1600702
Alternate Identifier(s):
OSTI ID: 1658369
Grant/Contract Number:  
FG02-95ER54309; FC02-04ER54698; SC0018992
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 60; Journal Issue: 3; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; NTV flux; density pumpout; ELM control

Citation Formats

Liu, Yueqiang, Paz-Soldan, C., Li, Li, and Sun, Youwen. Role of 3D neoclassical particle flux in density pump-out during ELM control by RMP in DIII-D. United States: N. p., 2020. Web. https://doi.org/10.1088/1741-4326/ab6c35.
Liu, Yueqiang, Paz-Soldan, C., Li, Li, & Sun, Youwen. Role of 3D neoclassical particle flux in density pump-out during ELM control by RMP in DIII-D. United States. https://doi.org/10.1088/1741-4326/ab6c35
Liu, Yueqiang, Paz-Soldan, C., Li, Li, and Sun, Youwen. Tue . "Role of 3D neoclassical particle flux in density pump-out during ELM control by RMP in DIII-D". United States. https://doi.org/10.1088/1741-4326/ab6c35. https://www.osti.gov/servlets/purl/1600702.
@article{osti_1600702,
title = {Role of 3D neoclassical particle flux in density pump-out during ELM control by RMP in DIII-D},
author = {Liu, Yueqiang and Paz-Soldan, C. and Li, Li and Sun, Youwen},
abstractNote = {The application of three-dimensional (3D) resonant magnetic perturbations, for the purpose of controlling edge localized modes (ELMs) in high confinement (H-mode) tokamak fusion operations, routinely leads to a significant reduction of the plasma density during the discharge, a phenomenon termed ‘density pump-out’. Understanding the density pump-out phenomenon due to 3D fields is a longstanding challenging issue. This work reports a self-consistent toroidal model that allows initial value simulation of the density pump-out effect. The model successfully reproduces pump-out phenomenology in DIII-D ELM suppression experiments. The radial particle flux, associated with the 3D neoclassical effects (the neoclassical toroidal viscosity, NTV), is found to play an important role in producing the observed large density pump-out. The key physics is associated with the drift kinetic Landau resonances between the toroidal precession of trapped thermal ions and electrons from one side, and the magnetic field perturbation from the other side. Such resonances, occurring near the top of the pedestal region, substantially enhances the radial particle flux associated with NTV. As a general consequence of the resonant NTV flux, larger density pump-out occurs in plasmas with lower collisionality and slower toroidal rotation.},
doi = {10.1088/1741-4326/ab6c35},
journal = {Nuclear Fusion},
number = 3,
volume = 60,
place = {United States},
year = {2020},
month = {2}
}

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