Towards a 240 GHz Megawatt-Class Gyrotron for Proxima Alpha

Karlsruhe Institute of Technology (KIT) is advancing the research and development of a short-pulse pre-prototype as the base for a continuous-wave (CW) industrial gyrotron with an output power exceeding 1 Megawatt (MW) at an operating frequency of around 240 GHz. It shall become the key component of an Electron Cyclotron Resonance Heating (ECRH) system for a future fusion power plant operating at a toroidal magnetic field of around 9 Tesla, specifically designed for Proxima Alpha. The pre-prototype shall be built-up and tested at the KIT FULGOR gyrotron test-facility, that will receive a 10.5 Tesla superconducting gyrotron magnet latest by 2025. This paper outlines the development for advancing the 240 GHz gyrotron. Possible designs are evaluated for their potential to manage the thermal loading, to minimize mode competition, and, to advance operating stability. The fundamental design choices and key challenges, including thermal management, cavity mode selection, and precision alignment, as well as simulation results for electron beam propagation and cavity performance are discussed.