Numerical simulation of radial three-cavity transit time oscillator
A new low-impedance of HPM source called radial three-cavity transit time oscillator is proposed based on the transition radiation and the low-impedance character of the radial structure.The oscillator is consisted of three side-coupling coaxial cavities which have the same cavity height.Circle symmetrical models are designed to effect with the electrons which moving in the radial direction.Through the PIC simulation,A C-band oscillator is designed,and the average operation power of 7.4 GW at 4.1 GHz is obtained,when excited by a 450 keV,60 kA radial electron beam,with an impedance of 7.5 Ω.The vital character lines are obtained by simulation.Analysis result reveals that the oscillator has the basic characters of the transit time effect,and is of a transition radiation oscillator which has traits as follows: low impedance,high efficiency,less modes competition and low requirement for the characters of the electron beam.