Design of Thomson scattering diagnostic system on J-TEXT.

An infrared multi-channel Thomson scattering diagnostic system is designed from the viewpoint of development of the proposed system on the Joint Texas Experimental Tokamak (J-TEXT). A 3 J/50 Hz Nd:YAG laser, which is injected vertically into plasma in the direction from top to bottom, serves as the power source of the system. The scattering light is then collected horizontally and is transmitted to an interference-filter avalanche photodiode based polychromater for spectrum analysis. The system covers the half plasma cross section, providing 14 spatial points with 2 cm resolution. The proposed system can thus satisfy the requirements of the J-TEXT at present and in the near future. A detailed description of the system design is presented in this paper.