Soft and Ultra-Soft X-ray Detector Array Systems for Measurement of Edge MHD Modes in the Large Helical Device

Abstract

In the Large Helical Device (LHD), several 20-channel Soft X-ray (SX) detector arrays are used to observe the radial structures of SX fluctuations related to MHD instabilities. Recently, 20-channel absolute extreme ultraviolet (AXUV) detector arrays have also been installed inside the vacuum vessel in the vertically and horizontally elongated sections of LHD to monitor MHD fluctuations of AXUV emissions emitted from edge plasma region. These AXUV detector arrays have often detected edge MHD fluctuations localized in low temperature and density edge region so that the SX detector arrays cannot be detected. In LHD, these SX and AXUV detector array systems are successfully employed in order to investigate radial structure and temporal behaviors of edge MHD modes.