Preliminary Study of a Multiple-Beam Extended-Interaction Oscillator With Coaxial Structure

The applications of multiple beams in the extended-interaction oscillator (EIO) with coaxial structure permit a significant increase in the average output power at millimeter wavelength. The study of the TM mode in the coaxial structure shows it can operate in the base mode with a large diameter (relative to the operating wavelength). Through periodically connect the coaxial structure along the axis, the newly developed circuit is formed. The analysis of these circuits shows that the TM010 mode of the circuits with a large volume can interact with the multiple beams efficiently. To demonstrate this capability, a Ka-band EIO with coaxial structure has been designed. A five-beam with a total current of 6 A (evenly divided among five beams) at a voltage of 19 kV was used in this device. Simulations with a 3-D Particle-in-Cell-code computer simulation technology predict an output power up to 25 kW at 35.5 GHz; the efficiency is about 21.9%.