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Title: Suppression of Alfven Modes on the National Spherical Torus Experiment Upgrade with Outboard Beam Injection [Suppression of Alfven Modes on the NSTX-U with Outboard Beam Injection]

Abstract

In this paper we present data from experiments on the National Spherical Torus Experiment Upgrade, where it is shown for the first time that small amounts of high pitch-angle beam ions can strongly suppress the counterpropagating global Alfven eigenmodes (GAE). GAE have been implicated in the redistribution of fast ions and modification of the electron power balance in previous experiments on NSTX. The ability to predict the stability of Alfven modes, and developing methods to control them, is important for fusion reactors like the International Tokamak Experimental Reactor, which are heated by a large population of nonthermal, super-Alfvenic ions consisting of fusion generated alpha's and beam ions injected for current profile control. We present a qualitative interpretation of these observations using an analytic model of the Doppler-shifted ion-cyclotron resonance drive responsible for GAE instability which has an important dependence on k(perpendicular to rho L). A quantitative analysis of this data with the HYM stability code predicts both the frequencies and instability of the GAE prior to, and suppression of the GAE after the injection of high pitch-angle beam ions.

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1];  [1];  [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Univ. of California, Los Angeles, CA (United States)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
OSTI Identifier:
1377834
Alternate Identifier(s):
OSTI ID: 1372589
Grant/Contract Number:
AC02-09CH11466; FG02-99ER54527
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 118; Journal Issue: 26; Journal ID: ISSN 0031-9007
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; eigenmodes; tokamak; plasmas; waves; ions

Citation Formats

Fredrickson, E. D., Belova, E. V., Battaglia, D. J., Bell, R. E., Crocker, N. A., Darrow, D. S., Diallo, A., Gerhardt, S. P., Gorelenkov, N. N., LeBlanc, B. P., and Podesta, M.. Suppression of Alfven Modes on the National Spherical Torus Experiment Upgrade with Outboard Beam Injection [Suppression of Alfven Modes on the NSTX-U with Outboard Beam Injection]. United States: N. p., 2017. Web. doi:10.1103/PhysRevLett.118.265001.
Fredrickson, E. D., Belova, E. V., Battaglia, D. J., Bell, R. E., Crocker, N. A., Darrow, D. S., Diallo, A., Gerhardt, S. P., Gorelenkov, N. N., LeBlanc, B. P., & Podesta, M.. Suppression of Alfven Modes on the National Spherical Torus Experiment Upgrade with Outboard Beam Injection [Suppression of Alfven Modes on the NSTX-U with Outboard Beam Injection]. United States. doi:10.1103/PhysRevLett.118.265001.
Fredrickson, E. D., Belova, E. V., Battaglia, D. J., Bell, R. E., Crocker, N. A., Darrow, D. S., Diallo, A., Gerhardt, S. P., Gorelenkov, N. N., LeBlanc, B. P., and Podesta, M.. Thu . "Suppression of Alfven Modes on the National Spherical Torus Experiment Upgrade with Outboard Beam Injection [Suppression of Alfven Modes on the NSTX-U with Outboard Beam Injection]". United States. doi:10.1103/PhysRevLett.118.265001. https://www.osti.gov/servlets/purl/1377834.
@article{osti_1377834,
title = {Suppression of Alfven Modes on the National Spherical Torus Experiment Upgrade with Outboard Beam Injection [Suppression of Alfven Modes on the NSTX-U with Outboard Beam Injection]},
author = {Fredrickson, E. D. and Belova, E. V. and Battaglia, D. J. and Bell, R. E. and Crocker, N. A. and Darrow, D. S. and Diallo, A. and Gerhardt, S. P. and Gorelenkov, N. N. and LeBlanc, B. P. and Podesta, M.},
abstractNote = {In this paper we present data from experiments on the National Spherical Torus Experiment Upgrade, where it is shown for the first time that small amounts of high pitch-angle beam ions can strongly suppress the counterpropagating global Alfven eigenmodes (GAE). GAE have been implicated in the redistribution of fast ions and modification of the electron power balance in previous experiments on NSTX. The ability to predict the stability of Alfven modes, and developing methods to control them, is important for fusion reactors like the International Tokamak Experimental Reactor, which are heated by a large population of nonthermal, super-Alfvenic ions consisting of fusion generated alpha's and beam ions injected for current profile control. We present a qualitative interpretation of these observations using an analytic model of the Doppler-shifted ion-cyclotron resonance drive responsible for GAE instability which has an important dependence on k(perpendicular to rho L). A quantitative analysis of this data with the HYM stability code predicts both the frequencies and instability of the GAE prior to, and suppression of the GAE after the injection of high pitch-angle beam ions.},
doi = {10.1103/PhysRevLett.118.265001},
journal = {Physical Review Letters},
number = 26,
volume = 118,
place = {United States},
year = {Thu Jun 29 00:00:00 EDT 2017},
month = {Thu Jun 29 00:00:00 EDT 2017}
}

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