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Title: Beta limit due to m/n = 2/1 tearing mode onset in the DIII-D hybrid scenario

Abstract

The performance (βN ≈ 3, q95 ≈ 4.4, fBS ≈ 0.5, H89 > 2) of hybrid scenario plasmas in DIII-D is limited by m/n = 2/1 tearing modes. Unlike conventional plasmas, the linear dependence scaling of the global beta for onset of the instability with normalized local ion gyroradius ρi* is modified as the n = 1 ideal kink beta limit is approached, suggesting that small island neoclassical tearing mode (NTM) threshold physics does not impose the dominant criterion for NTM stability. The hybrid scenario tends to go unstable just at or below the no wall n = 1 ideal kink beta limit of about 4l. Experimentally 4li decreases with beta as 4li ≈ 5.7 βN-1/2. Thus the 'ceiling' in beta due to coupling of tearing to the ideal kink comes down as beta is increased. Scaling of the tearing unstable beta that combines both NTM threshold physics and a pole in Δ'r due to coupling to the ideal kink is presented

Authors:
 [1];  [1];  [2]
  1. General Atomics, San Diego, CA (United States)
  2. Univ. of Tulsa, OK (United States)
Publication Date:
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
OSTI Identifier:
1170913
Resource Type:
Journal Article
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 48; Journal Issue: 1; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

La Haye, R. J., Politzer, P. A., and Brennan, D. P. Beta limit due to m/n = 2/1 tearing mode onset in the DIII-D hybrid scenario. United States: N. p., 2008. Web. doi:10.1088/0029-5515/48/1/015005.
La Haye, R. J., Politzer, P. A., & Brennan, D. P. Beta limit due to m/n = 2/1 tearing mode onset in the DIII-D hybrid scenario. United States. https://doi.org/10.1088/0029-5515/48/1/015005
La Haye, R. J., Politzer, P. A., and Brennan, D. P. 2008. "Beta limit due to m/n = 2/1 tearing mode onset in the DIII-D hybrid scenario". United States. https://doi.org/10.1088/0029-5515/48/1/015005.
@article{osti_1170913,
title = {Beta limit due to m/n = 2/1 tearing mode onset in the DIII-D hybrid scenario},
author = {La Haye, R. J. and Politzer, P. A. and Brennan, D. P.},
abstractNote = {The performance (βN ≈ 3, q95 ≈ 4.4, fBS ≈ 0.5, H89 > 2) of hybrid scenario plasmas in DIII-D is limited by m/n = 2/1 tearing modes. Unlike conventional plasmas, the linear dependence scaling of the global beta for onset of the instability with normalized local ion gyroradius ρi* is modified as the n = 1 ideal kink beta limit is approached, suggesting that small island neoclassical tearing mode (NTM) threshold physics does not impose the dominant criterion for NTM stability. The hybrid scenario tends to go unstable just at or below the no wall n = 1 ideal kink beta limit of about 4l. Experimentally 4li decreases with beta as 4li ≈ 5.7 βN-1/2. Thus the 'ceiling' in beta due to coupling of tearing to the ideal kink comes down as beta is increased. Scaling of the tearing unstable beta that combines both NTM threshold physics and a pole in Δ'r due to coupling to the ideal kink is presented},
doi = {10.1088/0029-5515/48/1/015005},
url = {https://www.osti.gov/biblio/1170913}, journal = {Nuclear Fusion},
issn = {0029-5515},
number = 1,
volume = 48,
place = {United States},
year = {Tue Jan 01 00:00:00 EST 2008},
month = {Tue Jan 01 00:00:00 EST 2008}
}