Study of poloidal rotation induced by inboard-outboard asymmetry of NBI momentum input in KSTAR based on the gyro-center shift

The experimental measurement and theoretical analysis are performed for the origin of poloidal rotation by Neutral Beam Injection (NBI) momentum input. The theory of Gyro-Center Shift (GCS) suggests the radial electric field formation by the perpendicular component of NBI momentum input [1]. Most of induced ExB drift is balanced with the parallel rotation so that the plasma rotation is purely toroidal but there are regions where the induced radial electric field generates poloidal rotation since NB is injected into the same flux tube with different pitch angles when it propagates at inboard side and outboard side. The poloidal rotation measurements from Beam Emission Spectroscopy (BES) for the edge region and X-Ray Imaging Chrystal Spectrometer (XICS) for the core region with analysis using NUBEAM code will be presented. \\[4pt] [1] K. C. Lee, ``Analysis of Turbulence Diffusion and H-mode Transition in Conjunction with Gyrocenter Shift at the boundary of Fusion Devices,'' \textit{Plasma Phys. Cont. Fusion}, 51, 065023 (2009).