Design of a dual scattering angle multi-pass Thomson scattering system with signal separation function on Heliotron J

This paper proposes a design of dual scattering angles multi-path Thomson scattering system with a signal separation function to solve the overlapping phenomenon of scattered light signals and to increase the measurement accuracy for the investigation of anisotropic electron velocity distribution. Furthermore, an optical path design is proposed to demonstrate how overlapping scattered light signals can be separated by setting the optical path in a limited room with a compact layout, which makes the incident interval between two overlapping scattered light signals 1.7 times longer than that of our current system. The specific position of each optical component existing in the system is determined via a Gaussian beam analysis to avoid damage caused by overexpansion of spot size with the application of two cooperating image relay systems. Conversely, a polychromator is optimized by resetting the pass waveband of the interference filter combination to achieve high accuracy in electron temperature (T_e) measurement corresponding to two scattering angles simultaneously.