Wideband polarizer for JT-60SA

Metal Technology Company has conducted collaborative research with members of the Quantum Science and Technology Research and Development Organization (QST), and Ibaraki University (Saegusa Laboratory) on the ECH (electron cyclotron resonance heating) of the superconducting tokamak plasma nuclear fusion experiment device “JT-60SA”. We have developed a high power wide-band polarizer compatible at millimeter wave of megawatts level.

The wide-band polarizer for millimeter waves successfully developed this time can transmit, with high efficiency, high power millimeter waves (frequency: 110 GHz, 138 GHz) for heating plasma. The polarizer, through its metal mirror which is equipped with a rotatable reflective diffraction grating, can produce arbitrary polarized waves which can enter the plasma. Through continued collaborative research the heat loss was reduced to 50% or less, the size was reduced by about 4 kg, and the cooling efficiency was improved in comparison to the prototype type.

Heat transfer analysis and structural analysis were carried out to design an optimum cooling structure. A reduction in size was achieved by optimizing the structure. In addition, the metal mirror section with the diffraction grating and it’s very strict dimensional requirements was achieved through Metal Technology’s high precision machining technology.

N. HORIE, K. OMORI, A. OMORI, M. SAIGUSA, T. KOBAYASHI, S. MORIYAMA, H. ARATA, T. UNO, "High Power Test of Wideband Polarizer for Electron Cyclotron Current Driving System in JT-60SA" , Submit to Fusion Engineering and Design.