Simulation research of a new transit-time oscillator

A new low-impedance axial transit-time oscillator with six cavities at C-band was designed, based on three-cavity transit time oscillator(TTO). The impedance of this oscillator is about 15 Ω, the microwave is exported in coaxial wave-guide. The oscillator possesses a large area cathode without extra magnetics. The oscillator is simulated in 2D model by 2.5-dimentional PIC code, the peak values of input voltage and current are 483 kV and 32.5 kA respectively; the average peak value of output microwave is over 3.0 GW, the main frequency is 3.75 GHz. The power efficiency of microwave is above 19% and better than that of the normal low-impedance osillators.