LHD Thomson Scattering Diagnostics

Abstract Thomson scattering diagnostic systems are widely used to measure the local electron temperature and density of plasmas, which are one of the most important plasma parameters. The Large Helical Device (LHD) Thomson scattering system was designed and developed from 1991 to 1998, and has been in operation without any major problem since the LHD second experiment campaign in 1998. The LHD Thomson scattering system measures the pseudo-continuous time evolution of electron temperature and density profiles at 144 spatial points along the LHD major radius. The LHD Thomson scattering system can measure electron temperature and density spatially from the inner boundary to the outer boundary, and temporally from the birth to the destruction of LHD plasmas. The performance is still one of the best in the world. In this paper, we discuss improvements and newly obtained results of this system with emphasis on the results from 2010 to 2024.