Design study of a new antenna system for steering microwave beam in electron cyclotron heating/current drive system

Moriyama, Shinichi; Seki, Masami; Fujii, Tsuneyuki

A power measurement method for an electron cyclotron heating (ECH) system using a ceramic disk was studied and tested. A model calculation showed that the disk edge temperature of the diamond vacuum window was sufficient to estimate the transmission power at 1 MW and 110 GHz with a response time of 0.2 s. The initial high power test with very thin thermocouple demonstrated successful power measurement with response time of 1.0 s. The concept of the linear motion ECH antenna suitable for reactor (like) environment is newly introduced and studied. A typical design would involve a mm-wave beam reflected at a flat mirror and a concave mirror. In the second reflection, the reflection angle can be changed by varying the point of reflection. The point of reflection is easily controlled by the linear movement of either the flat mirror or the concave mirror. It is notable that mirror rotation, which may require regular maintenance, is not required and backlash can be eliminated.