Analysis of baffles for stray light reduction in the Thomson scattering diagnostic on EAST

Abstract

Baffle is a critical technique to suppress stray light. In order to reduce stray light of EAST Thomson scattering (TS) diagnostic system, a 60° cone angle double edged baffle array was installed for the system. Recently the 45° cone angle corrugation baffle was designed based on double edged baffle and simulation results indicate that the new design can reject 33.3% more stray light than the old one. Based on the mechanical structure and surface property of EAST TS diagnostic system, a stray light analysis model has been built, and using the model, stray light of the system was simulated with the two types of baffles added to the system respectively. Results show that the installation of 60° cone angle double edged baffle array in input tube can cut 92.1% of the stray light to the system, while using 45° cone angle corrugation baffle array in input tube and three 45° cone angle corrugation baffles in exit tube, additional 74.1% of the stray light will be removed.