ELM-free and inter-ELM divertor heat flux broadening induced by Edge Harmonics Oscillation in NSTX

Gan, K.; 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.
Issue date: 2017
Rights:
Creative Commons Attribution 4.0 International (CC BY)
Cite as:
Gan, K., 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. (2017). ELM-free and inter-ELM divertor heat flux broadening induced by Edge Harmonics Oscillation in NSTX [Data set]. Princeton Plasma Physics Laboratory, Princeton University. https://doi.org/10.11578/1562042
@electronic{gan_k_2017,
  author      = {Gan, K. 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.},
  title       = {{ELM-free and inter-ELM divertor heat flu
                x broadening induced by Edge Harmonics O
                scillation in NSTX}},
  publisher   = {{Princeton Plasma Physics Laboratory, Pri
                nceton University}},
  year        = 2017,
  url         = {https://doi.org/10.11578/1562042}
}
Description:

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 (?_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.

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