ITER EC system includes equatorial port launcher and upper port launchers as RF power injection device. To select the operating launcher, the waveguide switch in transmission line (TL) is used and its operation is required even during plasma operation also, namely mid-pulse switch operation. To change the waveguide switch the gyrotron has to stop RF power during the switch operation since the direction is changed by mechanical movement of mirror position which takes a few seconds. Since ITER EC system is based on multi-subsystem concept, each subsystem has its own subsystem control unit (SCU) and EC main controller supervises all subsystem controllers. Hence cooperative operation requires to share the information of both RF power status and switch status between gyrotron SCU and TL SCU via main controller. The design of inter-subsystem control scheme is key issue for ITER EC system control and its evaluation is required. In QST, gyrotron and ITER relevant TL test stand were utilized for demonstration of mid-pulse switch operation. For this purpose, SCUs for each subsystem and main controller were developed using ITER relevant control system. The operation of mechanical switch during gyrotron pulse was demonstrated. During the 150 sec operation of high power gyrotron at 400 kW level, waveguide switch in TL was operated to change the direction of RF power. The time duration for switch operation with inter subsystem control scheme took 1.5 sec in total. The synchronizing of RF power suspend and resume with switch motion has been realized and RF power direction control during the gyrotron operation was successfully demonstrated.29th Symposium on Fusion Technology (SOFT2016
