Electron Cyclotron Emission Imaging on the EAST Tokamak

An upgraded electron cyclotron emission imaging (ECEI) system consisting of new optics lenses with necessary electronics for receiving and processing signals for two dimension (2D) ECEI diagnostics was installed on EAST. Hyperboloid lens were adopted in the new system to optimize the spatial resolutions. The mixers array of sixteen elements measured the plasma electron cyclotron emission at eight frequencies simultaneously, and the profiles of the electron temperature and its fluctuation in an area of 20 cm (vertical) × 6 cm (horizontal) could then be analyzed. Eevolution of sawtooth precursor and crash in EAST was observed.