Investigation of transmission characteristic in corrugated waveguide transmission lines for fusion application

Takahashi, Koji; Kajiwara, Ken; Kasugai, Atsushi; Kobayashi, Noriyuki; Sakamoto, Keishi

The 170GHz, high power and long pulse (0.46MW/4min) experiment of the ITER relevant transmission line that consited of corrugated waveguides and 7 miterbends was demonstrated. The transmission efficiency was 92%, which was almost equivalent value to the ITER requirement. No clear peak of temperature increase corresponding to the beat wavelength of this waveguide between HE11 and HE12 and between HE11 and HE13 was observed. The significant temperature near and between the bends was, however, obtained. These results indicate that the content of HE12 and HE13 mode is extremely low and the bends generate the unexpected higher order modes. They are also reflected back to the propagating direction.