Efficiency Enhancement of a Millimeter-Wave, Two-Beam Extended Interaction Oscillator Based on All-Period Field Optimization

In this paper, a scheme by optimizing electric field distribution with a two-output structure of the extended interaction oscillator (EIOs) is proposed to permit a significant increase in the efficiency at Ka-band. The distribution of the axial electric field and the synchronous conditions are optimized to make more fast electrons of the entire two-beam EIO circuit fall into the deceleration region and transfer energy to the electric field. Simulation results show that the efficiency is firstly improved from 28 % to 41 % by optimizing the external Q (Q(e)), the beam perveance (P-t) and the last period. To further increase the efficiency, a peak output power of 254 kW and an efficiency of 50.8 % at 54 kV voltage and 4.6x2 A current is obtained by optimizing the all-period synchronous conditions. The idea of the optimization method provides an effective way to improve the efficiency of multibeam vacuum electronic devices at millimeter-wave and higher frequencies.