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Title: ELM-free and inter-ELM divertor heat flux broadening induced by edge harmonics oscillation in NSTX

Abstract

A new n =1 dominated edge harmonic oscillation (EHO) has been found in NSTX. The new EHO, rotating toroidally in the counter-current direction and the opposite direction of the neutral beam, was observed during certain inter-ELM and ELM-free periods of H-mode operation. This EHO is associated with a significant broadening of the integral heat flux width ($${{\lambda}_{\operatorname{int}}}$$ ) by up to 150%, and a decrease in the divertor peak heat flux by >60%. An EHO induced filament was also observed by the gas puff imaging diagnostic. The toroidal rotating filaments could change the edge magnetic topology resulting in toroidal rotating strike point splitting and heat flux broadening. Finally, experimental result of the counter current rotation of strike points splitting is consistent with the counter-current EHO.

Authors:
 [1];  [2];  [2];  [3];  [3];  [4];  [3];  [3];  [5];  [4];  [4];  [1]
  1. Univ. of Tennessee, Knoxville, TN (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  5. General Atomics, San Diego, CA (United States)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1432665
Grant/Contract Number:  
[AC02-09CH11466; AC05-00OR22725; SC0008309]
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
[ Journal Volume: 57; Journal Issue: 12]; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; heat flux width; edge harmonic oscillation; strike points splitting; NSTX

Citation Formats

Gan, K. F., Ahn, J. -W., Gray, T. K., Zweben, S. J., Fredrickson, E. D., Scotti, F., Maingi, R., Park, J. -K., Canal, G. P., Soukhanovskii, V. A., Mclean, A. G., and Wirth, B. D. ELM-free and inter-ELM divertor heat flux broadening induced by edge harmonics oscillation in NSTX. United States: N. p., 2017. Web. doi:10.1088/1741-4326/aa8c4a.
Gan, K. F., Ahn, J. -W., Gray, T. K., Zweben, S. J., Fredrickson, E. D., Scotti, F., Maingi, R., Park, J. -K., Canal, G. P., Soukhanovskii, V. A., Mclean, A. G., & Wirth, B. D. ELM-free and inter-ELM divertor heat flux broadening induced by edge harmonics oscillation in NSTX. United States. doi:10.1088/1741-4326/aa8c4a.
Gan, K. F., Ahn, J. -W., Gray, T. K., Zweben, S. J., Fredrickson, E. D., Scotti, F., Maingi, R., Park, J. -K., Canal, G. P., Soukhanovskii, V. A., Mclean, A. G., and Wirth, B. D. Thu . "ELM-free and inter-ELM divertor heat flux broadening induced by edge harmonics oscillation in NSTX". United States. doi:10.1088/1741-4326/aa8c4a. https://www.osti.gov/servlets/purl/1432665.
@article{osti_1432665,
title = {ELM-free and inter-ELM divertor heat flux broadening induced by edge harmonics oscillation in NSTX},
author = {Gan, K. F. and Ahn, J. -W. and Gray, T. K. and Zweben, S. J. and Fredrickson, E. D. and Scotti, F. and Maingi, R. and Park, J. -K. and Canal, G. P. and Soukhanovskii, V. A. and Mclean, A. G. and Wirth, B. D.},
abstractNote = {A new n =1 dominated edge harmonic oscillation (EHO) has been found in NSTX. The new EHO, rotating toroidally in the counter-current direction and the opposite direction of the neutral beam, was observed during certain inter-ELM and ELM-free periods of H-mode operation. This EHO is associated with a significant broadening of the integral heat flux width (${{\lambda}_{\operatorname{int}}}$ ) by up to 150%, and a decrease in the divertor peak heat flux by >60%. An EHO induced filament was also observed by the gas puff imaging diagnostic. The toroidal rotating filaments could change the edge magnetic topology resulting in toroidal rotating strike point splitting and heat flux broadening. Finally, experimental result of the counter current rotation of strike points splitting is consistent with the counter-current EHO.},
doi = {10.1088/1741-4326/aa8c4a},
journal = {Nuclear Fusion},
number = [12],
volume = [57],
place = {United States},
year = {2017},
month = {10}
}

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