The progress in development of edge tangential Thomson scattering system on HL-2A tokamak

The edge tangential Thomson scattering system (ETTSS) was developed for the first time on a HL-2A tokamak. A Nd:YAG laser with a 1064 nm wavelength, 4 J energy, and 30 Hz repetition rate is employed on the ETTSS. The laser beam injects the plasma in the tangential direction on the mid-plane of the machine, and the angles between the laser injection direction and the scattered light collection direction are in the range from 157.5° to 162.8°. The scattered light collection optics with 0.21-0.47 magnification is utilized to collect the scattered light of measurement range from R = 1900 mm to 2100 mm (the normalized radius is from r/a = 0.625 to 1.125). Spatial resolution of the preliminary design could be up to Δr/a = 0.016. The measurement requirements could be achieved: 10 eV < Te < 1.5 keV, and 0.5 × 10¹⁹ m^-3 < n_e < 3 × 10¹⁹ m^-3 with errors less than 15% and 10%, respectively.