A type of silicon detector known as AXUV （absolute extreme ultraviolet） photodiodes is successfully used to measure the radiated power in EAST. The detector is characterized by compact structure, fast temporal response （〈0.5 s） and flat spectral sensitivity in the range from ultra-violet to X-ray. Two 16-channel AXUV arrays are installed in EAST to view the whole poloidal cross-section of plasma. Based on the diagnostic system, typical radiation distributions for both limiter and divertor plasma are obtained and compared. As divertor detachment occurs, the radiation distribution in X-point region is observed to vary distinctly. The total radiation power losses in discharges with different plasma parameters are briefly analyzed.
A compound sawtooth with an incomplete relaxation was observed in EAST＇s lower hybrid current drive （LHCD） plasma. The sub-crash phase of the compound sawtooth corresponds to a longer-lasting and slower-growing 1/1 mode. Based on the two-dimensional （2D） SXR tomography, the time-dependent 2D image of a compound sawtooth crash is obtained. The island produced during a resistive internal kink mode is observed in the all crash phases of the compound sawtooth. The destabilization of 1/I long-lasting saturated 1/1 mode is related to the current driven by the LHCD near the q = 1 surface.
