Research on the magnetic focusing system for 0.22 THz FWG-TWT

Abstract:

In the design of 0.22 THz Folded Waveguide Traveling-Wave Tube(FWG-TWT) which acts as an amplifier in terahertz sources，a magnetic focusing system is employed to ensure the beam from the electron gun moving into the beam-wave interaction region with high passing rate. The paper studies two kinds of magnetic focusing system，including solenoid and Periodic Permanent Magnet(PPM). Three-dimensional software is used to simulate the model and analyze how such parameters as magnetic pole position，period，flux density，even magnet pole’s thickness determine the beam’s transmission. The results show that the static passing rate of electron beam in the tunnel can almostly achieve 100%，with a small oscillating range of beam.