High power transmission and polarization measurement in 110 GHz transmission line

Efficient transmission and polarization in 110 GHz transmission line for JT-60U was studied. A 40-m run transmission test line (inner diameter of 31.75 mm) with eight miter bends, which included a pair of polarizers was designed and constructed. The transmission at 1 MW was performed and the transmission efficiency of 89% (without mirror optical unit (MOU)) was obtained. In basis of the good result, a 1 MW, 110 GHz electron cyclotron range of frequency (ECRF) system was constructed in JT-60U. Transmissions of 1 MW-2.0 s and 0.32 MW-5.0 s were performed in JT-60U ECRF system. The polarization of the transmitted wave in the transmission line was measured and the dependence of plasma electron heating on polarization was investigated. The optimum elliptical polarization of the incidence wave for the ECRF experiments in JT-60U was calculated using the cold dispersion relation with the measured polarization. The optimum polarization was applied to the electron heating experiment of JT-60U. (C) 2001 Elsevier Science B.V. All rights reserved.