Design of beam transmission system for 0.3 THz folded waveguide traveling wave amplifier

The THz folded waveguide (FWG) traveling wave amplifier (TWA) which is regarded as an important source in vacuum electronics is developed at Institute of Electronics, Chinese Academy of Science (IECAS). In this scheme, the circular electron beam is adopted, which can be gained the high current density of electron beam by the confined and immersed magnetic field. The folded waveguide high frequency structure is used as beam-wave interaction system. For the improvement output characteristics of THz FWG TWA, the beam transmission system is firstly designed and developed. The new-type cathode is developed, the current density can be obtained the 86.2 A/cm² at the operation temperature 1100 °C. The focusing magnetic field is designed, in which the permanent field system is used and tested, the peak strength of magnetic field can exceed over 4000 Gauss.