Study of a 0.35 THz extended interaction oscillator driven by a pseudospark-sourced sheet electron beam

A compact high-power extended interaction oscillator (EIO) driven by a pseudospark-sourced (PS-sourced) sheet electron beam (SEB) is presented at 0.35 THz. It combines the advantages of a planar interaction circuit and a SEB generated from the PS discharge, including a large beam cross-section, high gain per unit length, and high current density with the additional benefit of not requiring an external focusing magnetic field. Staying within what is achievable with microfabrication techniques, the influence of tolerance on the Q value, resonance frequency, and characteristic impedance was investigated. The effect of surface roughness caused by the manufacturing method on Ohmic loss of the material surface was studied. The advanced microfabrication techniques of Ultra Violet Lithographie, Galvanik, and Abformung (UV-LIGA) and Nano-computer numerical control (Nano-CNC), which are capable of realizing high precision and a metal surface of sufficient smoothness, were proposed to manufacture the planar structures. The effect of plasma density in PS-sourced SEB on the resonance frequency of the EIO circuit was investigated. The simulation results showed that the output signal had a slight frequency upshift and a decrease of the output power as the plasma density increased at 0.35 THz, which is consistent with the theoretical analysis. Beam-wave interaction simulations for this planar EIO predicted a peak output power of 1.8 kW at 0.35 THz using an effective value of conductivity of 1.1 × 10 ⁷ S/m to take into account the skin depth and surface roughness.