Microwave Reflectometer for Density Measurement on J-TEXT Tokamak

Microwave reflectometer is an essential diagnostic tool with high spatial and temporal resolution for the measurement of plasma density profile. In recent years, a microwave reflectometry system has been developed and optimized on the J-TEXT tokamak. It consists of three parts: Q band (33-50GHz) with extra-ordinary mode (X-mode), V band (50-75GHz) with X mode and Q band with ordinary mode (O-mode). Its measurement range covers from the edge to core of the low field side plasma. To obtain a linear frequency sweep, the dynamic calibration of the voltage control oscillator (VCO) is completed. The profile measured by the reflectometer is in good agreement with the result of the polarimetry.