Influence of Neutron Irradiation on the Large Helical Device Thomson Scattering System

Abstract

Since 2017, deuterium plasma experiments (DD experiments) have been performed in large helical device (LHD), where neutrons with a specific energy of 2.45 MeV are generated through deuterium thermonuclear fusion reactions, and the influence on the devices located near the LHD are concerned. For the LHD Thomson scattering system, a view window, a light collection mirror, and optical fibers have been installed near the LHD. Degradation by neutron irradiation may cause serious problems in the results from the Thomson scattering diagnostic. We discuss the calibration of the three components and the neutron influences on the LHD Thomson scattering diagnostics.