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

K. F. Gan; J. W. Ahn; T. K. Gray; S. J. Zweben; E. D. Fredrickson; F. Scotti; R. Maingi; J. K. Park; G. P. Canal; V. A. Soukhanovskii; A. G. McLean; B. D. Wirth

doi:10.1088/1741-4326/aa8c4a

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

K. F. Gan, J. W. Ahn, T. K. Gray, S. J. Zweben, E. D. Fredrickson, F. Scotti, R. Maingi, J. K. Park, G. P. Canal, V. A. Soukhanovskii, A. G. McLean, B. D. Wirth

Power Exhaust and Particle Control

Research output: Contribution to journal › Article › peer-review

7 Scopus citations

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 (λ_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. Experimental result of the counter current rotation of strike points splitting is consistent with the counter-current EHO.

Original language	English
Article number	126053
Journal	Nuclear Fusion
Volume	57
Issue number	12
DOIs	https://doi.org/10.1088/1741-4326/aa8c4a
State	Published - Oct 26 2017

Funding

This work was supported by the US DOE contract DE-AC05-00OR22725 (ORNL) and DE-SC0008309 (UTK).

Funders	Funder number
U.S. Department of Energy	DE-AC05-00OR22725
Oak Ridge National Laboratory	DE-SC0008309

Keywords

NSTX
edge harmonic oscillation
heat flux width
strike points splitting

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1088/1741-4326/aa8c4a

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@article{70807dd30bd24e53bbc7e12466392be1,

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 (λint) 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. Experimental result of the counter current rotation of strike points splitting is consistent with the counter-current EHO.",

keywords = "NSTX, edge harmonic oscillation, heat flux width, strike points splitting",

author = "Gan, {K. F.} and Ahn, {J. W.} and Gray, {T. K.} and Zweben, {S. J.} and Fredrickson, {E. D.} and F. Scotti and R. Maingi and Park, {J. K.} and Canal, {G. P.} and Soukhanovskii, {V. A.} and McLean, {A. G.} and Wirth, {B. D.}",

note = "Publisher Copyright: {\textcopyright} 2017 IAEA, Vienna.",

year = "2017",

month = oct,

day = "26",

doi = "10.1088/1741-4326/aa8c4a",

language = "English",

volume = "57",

journal = "Nuclear Fusion",

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TY - JOUR

T1 - ELM-free and inter-ELM divertor heat flux broadening induced by edge harmonics oscillation in NSTX

AU - Gan, K. F.

AU - Ahn, J. W.

AU - Gray, T. K.

AU - Zweben, S. J.

AU - Fredrickson, E. D.

AU - Scotti, F.

AU - Maingi, R.

AU - Park, J. K.

AU - Canal, G. P.

AU - Soukhanovskii, V. A.

AU - McLean, A. G.

AU - Wirth, B. D.

PY - 2017/10/26

Y1 - 2017/10/26

N2 - 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 (λint) 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. Experimental result of the counter current rotation of strike points splitting is consistent with the counter-current EHO.

AB - 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 (λint) 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. Experimental result of the counter current rotation of strike points splitting is consistent with the counter-current EHO.

KW - NSTX

KW - edge harmonic oscillation

KW - heat flux width

KW - strike points splitting

UR - http://www.scopus.com/inward/record.url?scp=85034250029&partnerID=8YFLogxK

U2 - 10.1088/1741-4326/aa8c4a

DO - 10.1088/1741-4326/aa8c4a

M3 - Article

AN - SCOPUS:85034250029

SN - 0029-5515

VL - 57

JO - Nuclear Fusion

JF - Nuclear Fusion

IS - 12

M1 - 126053

ER -

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

Abstract

Funding

Keywords

UN SDGs

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