Design and Analysis of a Magnetron Injection Gun for G-Band TE13 Mode Gyro-TWT

Electron beam transportation stability is important to the gyro-traveling-wave tube (gyro-TWT). For conventional G-band TE01 mode magnetron injection gun (MIG), the transportation performance is unsatisfactory because of the small interaction tunnel. For the transportation problem, a MIG with a slotted cathode for G-band TE13 mode gyro-TWT is proposed in this article. The MIG is designed and optimized, and a velocity ratio of 1.15 and a transverse velocity spread of 0.58% are obtained. Furthermore, the cathode has been produced and fabricated. A thermal test, a surface morphology test, and a computed tomography (CT) scan have been carried out. Then, beam quality and transportation stability are analyzed when thermal expansion, morphology deviation, stray electron, and magnetic field misalignment exist, respectively. The beam transportation performance is good under all conditions, and the total simulated velocity spread of the main electron is 3.3%.