A Poloidal CO₂ Laser Collective Scattering System for Measuring Electron-Scale Turbulence in the EAST

Anomalous electron thermal transport is an important issue that restricts the development of magnetic confinement thermonuclear fusion, and it is closely related to electron-scale turbulence. This paper introduces the poloidal CO2 laser collective scattering diagnostic system installed on the Experimental Advanced Superconducting Tokamak (EAST) for electron-scale turbulence measurement. The system can measure density fluctuations with four distinct wavenumbers simultaneously ranging from 10 to 30 cm(-1) (correspondingly k theta rho(s)similar to 1 to 5) in two regions (the core region rho approximate to 0 to 0.4 and the outer region rho approximate to 0.4 to 0:8), which realizes the spatial resolution for turbulence measurement. And, the plasma poloidal rotation velocity in these two regions can be calculated using the measured density fluctuation frequency. In addition, the characteristics of small scattering angle and negligible wave refraction effects reduce the size of the ports required for this diagnostic system. These advantages make the diagnostic system an effective tool for measuring electron-scale turbulence and may play an important role in future burning plasma experiments.