Development of Higher Efficiency MW-Power 230-GHz Gyrotron With Nonadiabatic Electron Gun

We study the possibility of implementing a higher efficiency gyrotron intended for plasma heating in advanced nuclear fusion facilities. To increase the efficiency above the standardly attainable value of about 50%, it is proposed to use an electron beam with a high oscillatory energy and a low-velocity spread, which can be formed in a nonadiabatic electron-optical system. Based on numerical simulations of electron–wave interaction, we demonstrate that the efficiency of a 230-GHz megawatt (MW)-level gyrotron with a single-stage energy recovery system can exceed 75%.