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Title: Mitigation of Alfven activity by 3D magnetic perturbations on NSTX

Abstract

Observations on the National Spherical Torus eXperiment (NSTX) indicatethat externally applied non-axisymmetric magnetic perturbations (MP) canreduce the amplitude of Toroidal Alfven Eigenmodes (TAE) and Global AlfvenEigenmodes (GAE) in response to pulsed n=3 non-resonant fields. Fromfull-orbit following Monte Carlo simulations with the 1- and 2-fluidresistive MHD plasma response to the magnetic perturbation included,it was found that in response to MP pulses the fast-ion losses increasedand the fast-ion drive for the GAEs was reduced. The MP did not affectthe fast-ion drive for the TAEs significantly but the Alfven continuumat the plasma edge was found to be altered due to the toroidal symmetrybreaking which leads to coupling of different toroidal harmonics. TheTAE gap was reduced at the edge creating enhanced continuum damping ofthe global TAEs, which is consistent with the observations. The resultssuggest that optimized non-axisymmetric MP might be exploited to controland mitigate Alfven instabilities by tailoring the fast-ion distributionfunction and/or continuum structure.

Creator(s)/Author(s):
; ; ; ; ; ; ; ; ; ;
Publication Date:
DOE Contract Number:  
AC02-09CH11466
Product Type:
Dataset
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
U. S. Department of Energy
Keywords:
fast ions
OSTI Identifier:
1562024
DOI:
10.11578/1562024

Citation Formats

Kramer, G J, Bortolon, A, Ferraro, N M, Spong, D A, Crocker, N A, Darrow, D S, Fredrickson, E D, Kubota, S, Park, J -K, Podesta, M, and Heidbrink, W W. Mitigation of Alfven activity by 3D magnetic perturbations on NSTX. United States: N. p., 2016. Web. doi:10.11578/1562024.
Kramer, G J, Bortolon, A, Ferraro, N M, Spong, D A, Crocker, N A, Darrow, D S, Fredrickson, E D, Kubota, S, Park, J -K, Podesta, M, & Heidbrink, W W. Mitigation of Alfven activity by 3D magnetic perturbations on NSTX. United States. doi:10.11578/1562024.
Kramer, G J, Bortolon, A, Ferraro, N M, Spong, D A, Crocker, N A, Darrow, D S, Fredrickson, E D, Kubota, S, Park, J -K, Podesta, M, and Heidbrink, W W. 2016. "Mitigation of Alfven activity by 3D magnetic perturbations on NSTX". United States. doi:10.11578/1562024. https://www.osti.gov/servlets/purl/1562024. Pub date:Mon Aug 01 00:00:00 EDT 2016
@article{osti_1562024,
title = {Mitigation of Alfven activity by 3D magnetic perturbations on NSTX},
author = {Kramer, G J and Bortolon, A and Ferraro, N M and Spong, D A and Crocker, N A and Darrow, D S and Fredrickson, E D and Kubota, S and Park, J -K and Podesta, M and Heidbrink, W W},
abstractNote = {Observations on the National Spherical Torus eXperiment (NSTX) indicatethat externally applied non-axisymmetric magnetic perturbations (MP) canreduce the amplitude of Toroidal Alfven Eigenmodes (TAE) and Global AlfvenEigenmodes (GAE) in response to pulsed n=3 non-resonant fields. Fromfull-orbit following Monte Carlo simulations with the 1- and 2-fluidresistive MHD plasma response to the magnetic perturbation included,it was found that in response to MP pulses the fast-ion losses increasedand the fast-ion drive for the GAEs was reduced. The MP did not affectthe fast-ion drive for the TAEs significantly but the Alfven continuumat the plasma edge was found to be altered due to the toroidal symmetrybreaking which leads to coupling of different toroidal harmonics. TheTAE gap was reduced at the edge creating enhanced continuum damping ofthe global TAEs, which is consistent with the observations. The resultssuggest that optimized non-axisymmetric MP might be exploited to controland mitigate Alfven instabilities by tailoring the fast-ion distributionfunction and/or continuum structure.},
doi = {10.11578/1562024},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2016},
month = {8}
}

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