Design of Permanent Magnetic Focusing System of Concentric Arc Folded Waveguide TWT

A magnet focusing system for W-band concentric arc folded-waveguide traveling wave tube (TWT) is developed. Based on the technical specifications of W band concentric arc folded waveguide TWT, a uniform permanent magnet focusing system is designed and tested. The beam tunnel is 0.3 mm and the length is 40.5 mm. The simulation result shows that when the voltage between the anode and cathode is 6 kV, a current of 120 mA can be generated, and the beam transmission rate is 100%. The test result is in agreement with the simulation result. The test result shows that the beam transmission rate is 90% with a voltage of 6 kV.