High-wavenumber Collective Scattering Diagnostic System for EAST and NSTX-U Tokamaks and Synthetic Diagnostic System Development*

A 693 GHz, 8-channel high-wavenumber scattering system is under development for NSTX-U and a 270 GHz 4-channel high-wavenumber scattering system is being installed on the EAST [1] tokamak. A synthetic diagnostic system is under development for assisting the design and data analysis of the high-k diagnostic systems on the NSTX [2] and EAST tokamaks. The high-k diagnostic system aims to study high-k electron density fluctuations, thereby providing a measurement of the -spectrum of the electron temperature gradient (ETG) [3] mode. Based on the previously developed beam tracing module, which accounts for both refraction and diffraction effects, the synthetic high-k system innovatively incorporates the 3D scattering volume; consequently, it can explore the impact of various factors (e.g. refraction, diffraction, curvature of the magnetic field, wavenumber alignment, and so on) on the scattering signal. The synthetic high-k system not only guides the design and setup of the actual high-k scattering system, aiding in better interpretation of experimental results, but it can also be adapted into other millimeter-wave/terahertz synthetic modules with beam tracing capabilities.