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Title: Global 3D Braginskii simulations of the tokamak edge region of IWL discharges

Abstract

A study of plasma turbulence and profile evolution in conditions of low (L-mode) and high (H-mode) confinement at the edge of an axisymmetric, nested circular flux-surface approximation to an inner wall limited (IWL) Alcator C-Mod discharge is presented, using numerical simulations with the global drift-ballooning (GDB) code. GDB solves drift-reduced Braginskii two-fluid equations for electromagnetic low-frequency turbulence in a 3D annulus centered on the last closed flux-surface (LCFS). Three simulations that investigate the conditions of a reference L-mode, a high density, and a high temperature (or H-mode-like) shot were performed using realistic parameters. L-mode transport appears to be largely driven by drift resistive ballooning structures. Its pressure profile exhibits a near-SOL breakpoint that Mirror Langmuir Probes (MLP) detect in C-Mod. The high density simulation sees an increase in the size of convective cells and enhanced turbulent transport, while H-mode conditions develop improved confinement, balanced $$E \times B$$ and ion diamagnetic drifts in the closed-flux region, and spontaneous generation of temperature pedestal with a density pedestal remaining absent. A statistical characterization of the turbulence both in the SOL and the closed-flux region is presented.

Authors:
 [1];  [1];  [1]
  1. Dartmouth College, Hanover, NH (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Laboratory-National Energy Research Scientific Computing Center
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1523624
DOE Contract Number:  
SC0010508; AC02-05CH11231
Resource Type:
Journal Article
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 57; Journal Issue: 11; Journal ID: ISSN 0029-5515
Country of Publication:
United States
Language:
English

Citation Formats

Francisquez, M., Zhu, B., and Rogers, B. N. Global 3D Braginskii simulations of the tokamak edge region of IWL discharges. United States: N. p., 2017. Web. doi:10.1088/1741-4326/aa7f23.
Francisquez, M., Zhu, B., & Rogers, B. N. Global 3D Braginskii simulations of the tokamak edge region of IWL discharges. United States. doi:10.1088/1741-4326/aa7f23.
Francisquez, M., Zhu, B., and Rogers, B. N. Fri . "Global 3D Braginskii simulations of the tokamak edge region of IWL discharges". United States. doi:10.1088/1741-4326/aa7f23.
@article{osti_1523624,
title = {Global 3D Braginskii simulations of the tokamak edge region of IWL discharges},
author = {Francisquez, M. and Zhu, B. and Rogers, B. N.},
abstractNote = {A study of plasma turbulence and profile evolution in conditions of low (L-mode) and high (H-mode) confinement at the edge of an axisymmetric, nested circular flux-surface approximation to an inner wall limited (IWL) Alcator C-Mod discharge is presented, using numerical simulations with the global drift-ballooning (GDB) code. GDB solves drift-reduced Braginskii two-fluid equations for electromagnetic low-frequency turbulence in a 3D annulus centered on the last closed flux-surface (LCFS). Three simulations that investigate the conditions of a reference L-mode, a high density, and a high temperature (or H-mode-like) shot were performed using realistic parameters. L-mode transport appears to be largely driven by drift resistive ballooning structures. Its pressure profile exhibits a near-SOL breakpoint that Mirror Langmuir Probes (MLP) detect in C-Mod. The high density simulation sees an increase in the size of convective cells and enhanced turbulent transport, while H-mode conditions develop improved confinement, balanced $E \times B$ and ion diamagnetic drifts in the closed-flux region, and spontaneous generation of temperature pedestal with a density pedestal remaining absent. A statistical characterization of the turbulence both in the SOL and the closed-flux region is presented.},
doi = {10.1088/1741-4326/aa7f23},
journal = {Nuclear Fusion},
issn = {0029-5515},
number = 11,
volume = 57,
place = {United States},
year = {2017},
month = {8}
}