Parametric Dependence Of Fast-ion Transport Events On The National Spherical Torus Experiment
Authors: E.D. Fredrickson, N.N. Gorelenkov, M. Podesta, A. Bortolon, S.P. Gerhardt, R.E. Bell, A. Diallo and B. LeBlanc
Abstract: Neutral-beam heated tokamak plasmas commonly have more than one third
of the plasma kinetic energy in the non-thermal energetic beam ion population.
This population of fast ions heats the plasma, provides some of the current
drive, and can affect the stability (positively or negatively) of magnetohydrodynamic
instabilities. This population of energetic ions is not in
thermodynamic equilibrium, thus there is free-energy available to drive
instabilities, which may lead to redistribution of the fast ion population.
Understanding under what conditions beam-driven instabilities arise, and the
extent of the resulting perturbation to the fast ion population, is important for
predicting and eventually demonstrating non-inductive current ramp-up and
sustainment in NSTX-U, as well as the performance of future fusion plasma
experiments such as ITER. This paper presents an empirical approach towards
characterizing the stability boundaries for some common energetic-ion-driven
instabilities seen on NSTX.
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2014 Nucl. Fusion 54 093007 doi:10.1088/0029-5515/54/9/093007
OSTI: I.D. 1148704
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