Start current study of a THz sheet beam extended interaction oscillator

Abstract

This paper presents a theoretical study on a start current of a 0.378 THz sheet beam extended interaction oscillator (SB-EIO), and the design of this device driven by thermionic cathode stands a chance to realize a compact and powerful THz coherent continuous radiation sources. After theoretical study, the SB-EIO with eleven gaps is designed to operate at 2π mode. The coupling and interaction abilities are optimized to meet the synchronization conditions and thus improve the output power and efficiency. The start current analysis is preliminarily accomplished, and the advantages are: (1) At the operation frequency of 0.378 THz, the start current and current density of the device are optimized to 20 A/cm2 and 8.4 mA, and the output power is 14 W. (2) It works in the condition of smooth copper plane in simulation, and the output power is still about 20 W when an electron beam with 252 mA and 41 kV is injected. The research gives an estimation of up to 3.5 times decline in output power when the surface roughness emerges. (3) The results of the simulation show that a relatively high efficiency of ∼13% in particle-in-cell (PIC) was observed, and a stable output power range from 98 W to 234 W is found when the injected electron beam (0.35 mm × 0.12 mm) is 16.8–42 mA and 42 kV. Moreover, the reliability of PIC results is verified in this paper.