Electron cyclotron emission diagnostics for the Compass Upgrade tokamak: preliminary quasi-optical design

Compass Upgrade (Compass-U) is a medium size (R = 0.894 m, a = 0.27 m) and high field (B_T ? 5 Tesla, I_p ? 2 MA) tokamak that is capable of addressing key challenges in magnetic fusion including power exhaust and advanced confinement regimes. Compass-U has recently entered the final design phase and is expected to have its first plasma in 2023. Electron cyclotron emission (ECE) will be available among first diagnostics and will provide measurements of high spatial and temporal resolution of electron temperature profile evolution through a radial view; a separate oblique view at 12° from normal will be installed to study non-thermal electrons. Both the radial and oblique views will be located in the wide-angle port which has dimensions that enable simultaneous hosting of the front-end of the quasi-optical (QO) paths for the two views. Each QO design will have an in-situ hot calibration source in the front-end to provide a stand-alone and calibrated T_e (R,t) measurements. Details of the diagnostic channels and beam resolution within the plasma will be presented.