PPPL-4729

Generation Of High Non-inductive Plasma Current Fraction H-mode Discharges By High-harmonic Last Wave Heating In The National Spherical Torus Experiment

Authors: G. Taylor, J.C. Hosea, C.E. Kessel, B.P. LeBlanc, D. Mueller, D.K. Phillips, E.J. Valeo, J.R. Wilson, P.M. Ryan, P.T. Bonoli, J.C. Wright and R.W. Harvey

Abstract:
1.4 MW of 30 MHz high-harmonic fast wave (HHFW) heating, with current drive antenna phasing, has generated a Ip = 300kA, BT (0) = 0.55T deuterium H-mode plasma in the National Spherical Torus Experiment that has a non-inductive plasma current fraction, fNI = 0.7 -1. Seventy-five percent of the non-inductive current was generated inside an internal transport barrier that formed at a normalized minor radius, r /a ~ 0.4 . Three quarters of the non-inductive current was bootstrap current and the remaining non-inductive current was generated directly by HHFW power inside r /a ~ 0.2.
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Submitted to: Physics of Plasmas (January 2012)

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