A tangential CO2 laser collective scattering system for measuring short-scale turbulent fluctuations in the EAST superconducting tokamak

A tangential CO2 laser collective scattering system has been first installed on the Experimental Advanced Superconducting Tokamak (EAST) to measure short-scale turbulent fluctuations in EAST plasmas. The system can measure fluctuations with up to four distinct wavenumbers simultaneously ranging from 10 cm−1 to 26 cm−1, and correspondingly k ⊥ ρ s ∼ 1.5 − 4.3 . The system is designed based on the oblique propagation of the probe beam with respect to the magnetic field, and thus the enhanced spatial localization can be achieved by taking full advantage of turbulence anisotropy and magnetic field inhomogeneity. The simultaneous measurements of turbulent fluctuations in different regions can be taken by special optical setup. Initial measurements indicate rich short-scale turbulent dynamics in both core and outer regions of EAST plasmas. The system will be a powerful tool for investigating the features of short-scale turbulent fluctuations in EAST plasmas.