Understanding ion cyclotron harmonic fast wave heating losses in the scrape off layer of tokamak plasmas
Authors: N. Bertelli, E. F. Jaeger, J. C. Hosea, C. K. Phillips, L. Berry, P. T. Bonoli, S. P. Gerhardt, D. Green, B. LeBlanc, R. J. Perkins, P. M. Ryan, G. Taylor, E. J. Valeo, J. R. Wilson and J. C. Wright
Abstract: Fast waves at harmonics of the ion cyclotron frequency, which have been used successfully on National Spherical Torus Experiment (NSTX) [1], will also play an important role in ITER and are a promising candidate for the Fusion Nuclear Science Facility (FNSF) designs based on spherical torus (ST) [2]. Experimental studies of high harmonic fast waves
(HHFW) heating on the NSTX have demonstrated that substantial HHFW power loss occurs along the open field lines in the scrape-off layer (SOL), but the mechanism behind the loss is not yet understood [3, 4, 5, 6, 7]. The full wave RF code AORSA [8], in which the edge plasma beyond the last closed flux surface (LCFS) is included in the solution domain [9], is applied
to specific NSTX discharges in order to predict the effects and possible causes of this power loss. In the studies discussed here, a collisional damping parameter has been implemented in AORSA as a proxy to represent the real, and most likely nonlinear, damping processes [10]. A prediction for the NSTX Upgrade (NSTX-U) experiment, that will begin operation next year,
is also presented, indicating a favorable condition for the experiment due to a wider evanescent region in edge density.*Research supported by the U.S. DOE under Contract No. DE-AC02-09CH11466 with Princeton University.
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Presented at: 41st European Physical Society (EPS) Conference on Plasma Physics, Berlin, June 23 27, 2014.
Published on-line in conference procedings: http://ocs.ciemat.es/EPS2014PAP/html/
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Download PPPL-5035 (pdf 2.3 MB 4pp)
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