Tractable Resonant Circuit with Two Nonuniform Beams for a High-Power 0.22-THz Extended Interaction Oscillator

In vacuum electronics, the influence of the uniformity of electron beams on the performance of two- or multi-beam devices is a key scientific problem in the development of compact, high power millimeter-wave and terahertz (THz) sources. In this letter, we focus on this problem in extended interaction oscillators (EIOs) and propose a tractable extended resonant circuit that has no requirement for the uniformity of beams. The circuit design builds up a TM13 mode mechanism to support two nonuniform beams, based on maintaining the same electromagnetic characteristics of conventional resonant circuits used in single-beam EIOs. To verify this idea, we designed and simulated a 0.22-THz EIO with the proposed circuit. As the current of one beam is I1 and that of another beam is increased from 0 to 4I1, the EIO has shown the behavior of linearly increasing the output power and then becoming saturated through particle-in-cell (PIC) simulations. The ideal case is the currents of the two beams are the same at the same voltage to drive the EIO. This case can reduce the high current density required for start oscillation in single-beam EIOs and obtain high power. Simulation results show that the power of 0.22-THz wave over 1.32 kW is obtained using double beams at 22.2 kV and each current of 0.25 A.