Progress on design and testing of corrugated waveguide components for ITER ECH&CD transmission lines

The performance requirement of 1 (possibly 2) MW cw at 170 GHz for ITER electron cyclotron heating & current drive transmission line components is much more demanding than the 1 MW, 5 to 10 s performance, generally at 110 GHz, that has been demonstrated on present devices. The high ITER heat loads will require enhanced cooling and, for some components, new or modified designs. In addition to thermal management issues, the components must be designed to have very low losses in order to meet the ITER transmission line efficiency requirements. Testing at representative ITER conditions of some components has been initiated at the JAEA 170 GHz gyrotron test stand at Naka, Japan. In addition, testing of a complete prototype ITER transmission line is planned in order to validate the designs for use on ITER. The design changes that are being made for the various components to assure low loss transmission and acceptable component temperatures are presented.