Design Of 20MW ECH Microwave System On CFETR Tokamak

Electron Cyclotron Resonance Heating (ECRH) and Electron Cyclotron Current Drive (ECCD) is one of the important auxiliary heating and non-inductive current drive methods in controllable nuclear fusion experiment. Therefore, Electron Cyclotron Wave (ECW) heating system is especially crucial to CFETR tokamak. According to the device parameter of CFETR tokamak, the operating frequency of the microwave source of ECW system is chosen as 170GHz and the total power injected into plasma is 20MW.In this paper, the overall design scheme of ECW heating system is introduced firstly. ECW heating system is composed of microwave subsystem, High Voltage Power Supply (HVPS) subsystem, monitor and control protection subsystem, vacuum subsystem and water-cooling subsystem. The microwave subsystem consists of microwave source, transmission line and launcher, which show the generating, transferring and injecting process of microwave respectively. HVPS is in charge of power supply for microwave source. Monitor and control protection subsystem, vacuum subsystem and water-cooling subsystem assure the safe and reliable operation of the overall ECW system.Then the microwave subsystem of ECW system is designed in detail. The design of microwave subsystem introduced with microwave source, transmission line and launcher three sections is shown as follow:(1) On the basis of the international development situation of gyrotron, the microwave source is made up of 20 170GHz/lMW long pulse gyrotrons. With the principles of decreasing occupied area of microwave source and easy routing of transmission line, the overall microwave source and the single gyrotron around are arranged reasonably. The total occupied area of microwave source is about 484 m2. In the end, from the perspective of future gyrotron development, the microwave source made up of 2MW long pulse gyrotron is also analyzed and arranged. (2) Supposing the microwave source is composed of lMW/170GHz long pulse gyrotrons, the layout of 20 transmission lines are designed. There are two design proposals of transmission line layout. After the choosing and arrangement of microwave devices in each transmission line, the power loss in each transmission line is about 8.7%. (3) Two types of launcher——equatorial launcher (EL) and upper launcher (UL) are designed with quasi-optics transferring pattern. The total launcher is installed on equatorial window or upper window with port-plug modular structure. In the detailed research of launcher, the injecting position and injecting angles of rotating injected mirror in launcher are calculated by C3PO/LUKE program firstly. Then according to the transmission characteristic of Gaussian beams, the transmission routes and converging status of all the wave beams are optimized by ZEMAX optical simulation software. After optimizing, the deploy of transmission lines in the launcher and the information of the optical mirrors can be gotten. In the next, the other devices in the launcher, such as water-cooling structure of the focusing mirror and rotating mirror, driving structure of the rotating mirror, blanket shield module, internal shield module, vacuum shielding, supporting structure and so on, are all explored. Finally, combining the electromagnetic simulation software MAXWELL and finite element analysis software ANSYS, the electromagnetic force deposited on the launcher is analyzed and the stress of the BSM resulting from electromagnetic force is evaluated.