Speaker
Description
The W-band doppler backscattering system on EAST, which was installed in 2018 [1], has been upgraded. The new design uses a beam splitter and two antennas to separate signal launching and receiving, thus avoiding signal noise caused by the reflection of the W-band filter. The frequency intervals between adjacent channels have been increased from 400 MHz to 1 GHz to broaden the diagnostic area. After carefully optimizing the power distribution between different channels, the maximum bandwidth is increased slightly from 97.8 GHz to 100.4 GHz and the performance in high frequency is significantly enhanced, which are more favorable for tokamak core turbulence measurements. Additionally, the corresponding ray tracing script [2] has been optimized by solving its numerical abrupt density change at the Last Closed Flux Surface, providing more reliable calculation results for the scattering position and wavenumber.
[1] Feng, X. et al. Five-channel tunable W-band Doppler backscattering system in the experimental advanced superconducting tokamak. Review of Scientific Instruments 90, 024704 (2019).
[2] Zhou, C. et al. Ray Tracing for Doppler Backscattering System in the Experimental Advanced Superconducting Tokamak. Plasma Sci. Technol. 17, 728–732 (2015).
