No abstract

The paper presents the development of sinusoidally grooved polarizers for electron cyclotron resonance heating (ECRH) systems in the HL-2A tokamak. The polarizer groove shape was designed according to a sinusoidal function with a groove period p = 0.48λ and depth d = 0.5λ. Here, λ is the wavelength, whose value is 4.41 mm. The low-power test results of the polarizer performance are in agreement with a numerical calculation based on the integral method developed in vector theories of diffraction gratings. High-power experiments reveal that 340 kW high-power EC waves can be transmitted through the corrugated waveguide line with the polarizer assembled in a miter bend at atmospheric pressure. With the polarizer, ECRH/electron cyclotron current drive (ECCD) experiments in the extraordinary mode have been successful in a HL-2A tokamak.