Proposal of new type diplexer for ECCD system

Saigusa, Mikio*; Sugawara, Shuhei*; Atsumi, Kohei*; Oda, Yasuhisa; Yamaguchi, Tomoki*; Sakamoto, Keishi

Neoclassical tearing modes (NTM) can be controlled by the local current drive in a magnetic island with electron cyclotron current drive (ECCD). For improving a stabilizing efficiency of NTM, the fast directional switch (FADIS) had been developed. In this paper, the new type diplexer as a fast switching device of high power millimetre wave is proposed for ECCD system in fusion devices. The principle is a ring resonator of oversized corrugated circular waveguide. The two half mirrors (dielectric disks or slotted antennae) are integrated in a ring resonator. The switching operation of a diplexer has been simulated with the code using finite differential time domain (FDTD) method. The switching operation of the diplexer by frequency shifting has been confirmed in the cases of dielectric disks or slotted antennae, where the loss caused by mode conversion and misalignment in a resonant ring are considered. A diplexer for 1 MW short pulse at a frequency of 170 GHz is designed and fabricated.