Concept of a megawatt power-level G-band planar gyrotron with transverse energy extraction

At present, the novel compact fusion reactors with strong magnetic fields, including the DEMO project, require the development of 220–240 GHz megawatt continuous-wave heating sources. In this paper, gyrotrons of planar geometry of interaction space with a sheet polyhelical electron beam and transverse energy extraction are considered as such sources. An advantage of this design in comparison with the conventional cylindrical gyrotron configuration is the possibility to ensure effective mode selection over the open transverse coordinate in combination with radiation outcoupling. The theoretical analysis and numerical 3D PIC simulations of a 230 GHz megawatt power planar gyrotron operating at the first harmonic of the cyclotron frequency are performed. The paper considers the feasibility of single-mode generation with output power exceeding 1 MW, efficiency of 30%, and Ohmic loads less than 1.5 kW/cm2, which is compatible with the continuous-wave operation regime.