Poloidal rotation velocity measurement with an MIR system on KSTAR

Abstract

A multi-channel microwave imaging reflectometry (MIR) system has been commissioned in the 2012 and 2013 KSTAR campaigns for the measurement of semi 2D (16 poloidal and 2 radial channels) electron density fluctuations for transport study on KSTAR. A time delayed cross correlation analysis among 16 poloidal channels has been applied to obtain the poloidal rotation velocities of the measured turbulent density fluctuations. The measured poloidal rotation directions for an 170 GHz ECH assisted ohmic plasma was in opposite direction to that of a neutral beam (NB) heated L-mode plasma. This is due to the fact that the intrinsic toroidal rotation in ohmic plasma (counter-clockwise) is in opposite direction to the NB heated plasma (clockwise) with respect to the plasma current direction.