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Title: Suppression of Alfvén modes on NSTX-U with outboard beam injection

Abstract

In this paper we present data from experiments on NSTX-U where it is shown for the first time that small amounts of high pitch-angle beam ions can strongly suppress the counter-propagating Global Alfvén 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 Alfvén modes, and developing methods to control them, is important for fusion reactor like the International Tokamak Experimental Reactor (ITER) which are heated by a large population of non-thermal, super-Alfvénic ions consisting of fusion generated alphas 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⊥ρL. 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.

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:
Global Alfven Eigenmodes; Energetic particles; Super-Alfvenic
OSTI Identifier:
1562055
DOI:
10.11578/1562055

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 Alfvén modes on NSTX-U with outboard beam injection. United States: N. p., 2017. Web. doi:10.11578/1562055.
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 Alfvén modes on NSTX-U with outboard beam injection. United States. doi:10.11578/1562055.
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. 2017. "Suppression of Alfvén modes on NSTX-U with outboard beam injection". United States. doi:10.11578/1562055. https://www.osti.gov/servlets/purl/1562055. Pub date:Thu Jun 01 00:00:00 EDT 2017
@article{osti_1562055,
title = {Suppression of Alfvén modes on 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 NSTX-U where it is shown for the first time that small amounts of high pitch-angle beam ions can strongly suppress the counter-propagating Global Alfvén 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 Alfvén modes, and developing methods to control them, is important for fusion reactor like the International Tokamak Experimental Reactor (ITER) which are heated by a large population of non-thermal, super-Alfvénic ions consisting of fusion generated alphas 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⊥ρL. 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 = {10.11578/1562055},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2017},
month = {6}
}

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Works referencing / citing this record:

Suppression of Alfvén Modes on the National Spherical Torus Experiment Upgrade with Outboard Beam Injection
journal, June 2017