Study of a rectangular coupled cavity extendedinteraction oscillator in sub-terahertz waves

An extended interaction oscillator (EIO) generating 120,GHz wave insub-terahertz waves is studied by using the three-dimensionalelectromagnetic simulation software CST and PIC codes. A rectangularreentrant coupled-cavity is proposed as the slow-wave structure ofEIO. By CST, the circuit parameters including frequency-phasedispersion, interaction impedance and characteristic impedance aresimulated and calculated. The operation mode of EIO is chosen veryclose to the point where $beta L=2pi$ with corresponding frequency120,GHz, the beam voltage 12,kV and the dimensions of the cavitywith the period 0.5,mm, the height 3,mm and the width 1.4,mm.Simulation results of beam--wave interaction by PIC show that theexciting frequency is 120.85,GHz and output peak power 465,W with12-period coupled-cavity with the perveance 0.17,$mu$P. Simulationresults indicate that the EIO has very wide range of the operationvoltage.