Development of a high power diplexer with short-slotted metal half mirrors for electron cyclotron current drive

A new type wideband diplexer as a fast switching device of high power millimeter wave has been developed for an electron cyclotron current driving system. A main purpose of fast switching is a stabilization of neoclassical tearing mode in tokamak plasmas. The short-slotted metal half mirror, which is one of the key components of a wideband diplexer is proposed. Two types of short-slotted metal half mirrors were designed and tested. One is periodic slot, and the other is non-periodic slot in a longitudinal direction. The switching operation of a mock-up diplexer with short-slotted metal half mirrors was verified at the frequency band from 169.5 GHz to 170.5 GHz at low power.