Development of the Real-time lmage Data Acquisition System for Observing the Plasma Dynamic Behavior of LHD Long-pulse Discharges

The experimental results of plasma dynamic behavior and impurity radiation profiles measured with tangentially viewing CCD cameras in Large Helical Device (LHD) are reported. The two dimensional profile of visible line emission from oxygen, carbon, helium and hydrogen has been measured. The cameras observed magnetic island structure in the plasma periphery and divertor magnetic field line structure. These structures are consistent with the calculations obtained by a multi-filament model. The image data taken with these cameras will give useful information for the analysis of the effect of the magnetic island on impurity transport and for designing a closed divertor configuration planned in Phase IL The image data acquisition system using data compression technique (MPEG-2) will be also described.