Design of high-power wideband polarizer for electron cyclotron resonance heating systems on CFETR

•The high-power wideband polarizer for the ECRH systems of CFETR is designed.•The polarization strategy with identical polarizer for ECRH systems of CFETR is used.•The polarization purity as a function of ratio of depth to wavelength is shown. The desired polarization for electron cyclotron resonance heating (ECRH) systems is generated by a pair of polarizers integrated into the transmission lines.This paper presents the design of a high-power wideband polarizer for 170-GHz and 230-GHz ECRH systems on China fusion engineering test reactor (CFETR). A low-loss, high-stability, and high-efficiency polarizer is required for multifrequency, high-power, and long-pulse ECRH systems to realize the arbitrary polarization state at different operating frequencies. Hence, two sinusoidal-grooved wideband polarizers with shallow grooves and identical parameters are designed herein. The polarization characteristics of wideband polarizer are presented for wideband polarizers at the frequency of 170-GHz and 230-GHz, in particular for the case using two identical polarizers consecutively. The results indicate that the two consecutive identical polarizers can achieve the arbitrary polarization state at frequencies of 170-GHz and 230-GHz.