Concept and Modeling of an Efficient, High Power, 0.35 THZ Source

High power, efficient THz sources have applications in wireless communications, radar, non-destructive testing, environmental sensing, THz spectroscopy, medicine and plasma diagnostics. High power radiation can be generated by guiding a thin, annular electron beam close to the corrugated inner wall of a cylindrical two-dimensional periodic surface lattice (2D PSL) interaction cavity. Theoretical and numerical studies of a 2D PSL designed to operate within an atmospheric window around 0.35 THz are presented. The shallow corrugation amplitude of 0.13 mm allows the 2D PSL to be described as an effective meta-dielectric 1 - 6 and the large mean diameter D=4.9mm (D/λ~5.6) enhances the output power of the device. Coupling of volume and surface modes can be observed when appropriate parameter values are chosen 1 - 5 . The resultant coupled eigenmode dominates over other competing modes within the oversized cavity. The axial period of the 2D PSL is shortened to d z =0.34mm to facilitate coupling with the 50kV electron beam. CST Microwave Studio PIC simulations demonstrate the powerful radiation output at 0.346 THz when an annular electron beam, immersed in a strong applied magnetic field of 5T, is passed through the 2D PSL of length 10d z and with 16 azimuthal variations. The pulsed source can deliver up to 50 kW of output power with an efficiency exceeding 25%.