Recent investigations of ELM crashes using ECE Imaging on DIII-D

DIII-D Electron Cyclotron Emission Imaging (ECEI) has been fully upgraded with 20 liquid crystal polymer (LCP) based integrated receiver chip modules for 2D electron temperature measurements. The new LCP modules have demonstrated significantly signal-to-noise improvement, which is over 20x better than previous minilens approach. All channels have been mapping in equilibrium and calibrated with the Thomson scattering diagnostic. The calibration coefficients are stable, which allows for the measurement of absolute temperature profiles with high temporal resolution (~ 1 microsecond). The temperature profile crash and recovery between ELMs has been captured. High speed measurements show that the pedestal temperature profile is flattened by an ELM crash. In the calibrated 2D temperature profile, the temperature gradient could be calculated during and after ELM crash. In additional, the higher harmonic electron temperature oscillation has been observed after sawtooth crash. The next generation of ECEI and Microwave Imaging Reflectometer (MIR) is under development for co-located and simultaneously electron temperature and density 2D imaging over a much wider range of plasma configurations.