Frequency Multiplication in Relativistic Gyrotrons for Providing High-Power Submillimeter Radiation

In order to provide high-power radiation in the submillimeter wavelength range, it is proposed to use the effect of frequency multiplication in high-current relativistic gyrotrons. As is known, as the energy of rotating electrons increases to relativistic values, the maximum of the electronwave coupling coefficients shifts towards higher cyclotron harmonics. We demonstrate that by multiplying the frequencies by a factor of three in a gyrotron with an operating frequency of 100 GHz and an electron beam with a moderately relativistic energy (500 keV),it is possible to achieve a megawatt power level in the 300 GHz band. The results were obtained in numerical simulation both within the framework of the averaged equations of the electron-wave interaction and when using the particle-in-cell code.