Application of Electron Beam Modulated Emission in a Novel Low Magnetic Field, High-Efficiency Q-Band Transit-Time Oscillator

A novel method to realize modulated emission and transmission in the diode region is proposed to improve beam-wave interaction for high output power and conversion efficiency. Microwave energy leaked into the diode is utilized to form a modulated electromagnetic field to modulate the emission and transmission of the electron beam. This mechanism is conducive to achieving better modulation effects of electron beam and suppressing competitive modes through the resonant frequency component of initial current modulation. A low magnetic field (0.7 T) Q-band relativistic coaxial transit time oscillator (RCTTO) is designed with this mechanism to obtain a microwave power of 337 MW, under the diode voltage of 396 kV and current of 1.98 kA. Compared with an RCTTO with a normal emission mechanism, the conversion efficiency increases from 21.3% to 43%.