Quasi-optical layout design of the ECRH equatorial launcher prototype towards the CFETR

The China Fusion Engineering Test Reactor (CFETR) is the proposed next-generation fusion facility in China. Currently, the crucial technology validation work for CFETR is in process. The Electron Cyclotron Resonance Heating (ECRH) system is one of the essential auxiliary heating systems for CFETR. The launcher is the key component of the ECRH system, responsible for injecting high-power microwave energy into the plasma. The propagation of wave beams in the launcher is usually achieved through quasi-optical systems, which are mainly composed of metal mirrors. To verify the key technologies of the launcher, an equatorial launcher is being developed. This paper presents the quasi-optical layout design and analysis of the prototype. A quasi-optical system consisting of two sets of fixed focusing mirrors and a steering plane mirror is designed. By analyzing the power tolerance within the equatorial port, a scheme for transmitting 6 beams within the launcher was obtained. According to the analysis of the transmission characteristics of the beams, the microwave performance of the launcher meets the device physical requirements. This work lays the foundation for subsequent engineering development.