Temporal Dynamics of NSTX NBI+HHFW Discharges using CQL3D-Hybrid-FOW*

The Fast Ion Diagnostic FIDA [1] signal resulting from neutral beam injection (NBI) and high harmonic fast wave (HHFW) RF power injected into the NSTX spherical tokamak has been simulated with the CQL3D Fokker-Planck code [2,3,4]. Motivated by a radial inward shift of the FIDA signal simulated with zero-orbit-width (ZOW) CQL3D compared to the large finite-orbit-width (FOW) NSTX experimental results [5], a 1st order correction was added which gave too large an outward shift [3]. More recent CQL3D FOW simulations based on guiding center orbits (plus gyro-width for losses) [4] produces quite accurate comparison with experiment. The modulated NBI and time-dependent background plasma variations are accounted for, also giving temporal neutron variation in rough agreement with NSTX observations.\\[4pt] [1] W. W. Heidbrink, et al. Plasma Phys. Controlled Fusion 46, 1855 (2004).\\[0pt] [2] R.W. Harvey and M. McCoy, ``The CQL3D Fokker Planck Code,'' http://www.compxco.com/cql3d.html.\\[0pt] [3] R.W. Harvey, et al., EPS, Strasbourg, Fr. (2011).\\[0pt] [4] Yu. Petrov and R.W. Harvey, this APS-DPP mtg (2012).\\[0pt] [5] M. Choi, et al., Phys. of Plasmas 17, 056102 (2010).