Polarization Research Of Electron Cyclotron Resonance Heating On The J-TEXT Tokamak

Owing to strong localized heating,high efficient coupling between wave and plasma,and long distance between the launcher and plasma,etc.,electron cyclotron resonance heating(ECRH)has become an important auxiliary heating method,and has been widely used in various domestic and foreign tokamak devices,such as ITER,for plasma heating,current drive,assistant start-up,current profile control,magnetohydrodynamic(MHD)instabilities control and transport study etc.The polarization and mode purity of electron cyclotron(EC)will affect the coupling efficiency between the wave and plasma,which will becomes an important factor for ITER or future fusion design.Based on the development of ECRH system for the J-TEXT tokamak of Huazhong University of Science and Technology,the single-frequency arbitrary periodic grooved polarizer and the 75-110 GHz broadband polarizer has been researched.And the arbitrary polarization of EC waves in single-frequency and broadband ranges has been realized.This research could provide reference for future research on polarizer design for high-power,high frequency and broadband ECRH systems.Firstly,a 60GHz/200kW/0.5s ECRH system from the Cluham Science Center of England has been reconstructed on the J-TEXT tokamak.Mainly,the 60 GHz superconducting magnet and transmission line has been restored and tested,and an 33kV/1A anode high voltage power supply(AHVPS)based on PSM technology has been developed and tested with the existing 100kV/60 A cathode high voltage power supply(CHVPS).A launcher,a deionized water cooling system and a control system have been developed and tested.Besides,on the basis of the original system,the AHVPS,the CHVPS,the deionized water cooling system,and the control system,etc.,have been upgraded,the 105 GHz transmission line and launcher have been designed and developed,the design of 105 GHz/500 kW/1s ECRH system has been completed.Secondly,the coordinate transformation method(C-method)has been used to design the arbitrarily grooved single-frequency polarizer and broadband polarizer.Compared with the integral method,the C-method can not only transform the groove boundary surface into a plane,which simplifies the boundary condition,but also change the complex vector integral calculation problem into a matrix eigenvalue problem,which is easier to implement in numerical applications.By comparing the numerical calculation results between the Cmethod and the vector integral method of the sinusoidal grooved polarizer,the scientificity and accuracy of the single-frequency point and broadband polarizer design using the Cmethod are verified.Then,the design of various single-frequency,such as sinusoidal,rectangular and trapezoidal,and sinusoidal broadband polarizers,has been carried out using C-method.The sinusoidal,rectangular and trapezoidal grooved single-frequency linear polarizers and elliptical polarizers,and the 75-110 GHz sinusoidal grooved broadband polarizers have been achieved.And the arbitrary polarization in single-frequency and broadband ranges has been achieved using dual polarizers.Among them,the sinusoidal grooved polarizer can effectively improve the power capacity,the rectangular or trapezoidal grooved polarizer can be easily processed for the high frequency ECRH system;the broadband polarizer can be applied to the future dual or multi-frequency ECRH system.It has already covered most of requirements related to future high frequency and high power broad-band ECRH polarization.Finally,we set up a low power test platform to carry out the experiments.The test results verified the correctness of design of single-frequency sinusoidal,rectangular and trapezoidal grooved polarizer and wide-band polarizers,and the reliability of dual polarizer combination for arbitrary poloarization.Meantime,The reliability of using the C-method to design arbitrary periodic grooved polarizers has been preliminarily verified.