A Polarizer with Sinusoidal Grooves in the Electron Cyclotron Resonance Heating System of the HL-2A Tokamak

摘要

Theoretical calculation and experimental results for a polarizer with sinusoidal grooves used in the electron cyclotron resonance heating (ECRH)system of the HL-2A tokamak are presented.The calculation is based on an integral method developed in the vector theory of diffraction gratings,and the polarization characteristics obtained with a low-power test are in good agreement with the numerical calculated results. With the polarizer assembled in a miter bend in the ECRH transmission line, pure ordinary mode(O-mode)and extraordinary mode(X-mode)polarized waves are also expected in the high-power experiment, depending on the polarizer rotation angle and the toroidal injection angle of the electron cyclotron(EC)wave beam.Second-harmonic X-mode experiments were successfully explored in HL-2A.Experimental result revealed that the electron temperature increased from 0.8 keV(Ohmic heating phase)to 1.5 keV(second X-mode heating phase).