A novel L-band metamaterial slow wave structure with low space charge effect and high field uniformity

A novel L-band metamaterial slow wave structure with a weak space charge effect and high field uniformity is proposed. The slow wave structure is composed of two identical all-metal resonant elements. In order to weaken the space charge effect, a long drift tube is adopted as a metal joint, connecting the front periodic unit with the rear one. Moreover, the novel metamaterial structure exhibits higher field uniformity by rotating one of the resonant elements 45 degrees relative to the other. Electromagnetic calculation indicates that the average fluctuation in the electric field dropped from 3% to 0.5%. Based on the novel metamaterial slow wave structure, an L-band Cerenkov oscillator model is built, and a preliminary particle-in-cell simulation is carried out. Under the condition of an acceleration voltage of 500 kV, beam current of 8 kA, and magnetic field of 1 T, a 1.64 GW average output microwave power at 1.30 GHz is obtained. The corresponding conversion efficiency is 41%. The simulation results prove the advantages of the metamaterial Cerenkov oscillator, such as low magnetic field, low impedance, miniaturization, and high conversion efficiency. (C) 2022 Author(s).