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A diode magnetron injection gun (MIG) has been designed and analyzed for G-band gyro-traveling wave tube (Gyro-TWT). A novel curved surface emitter is proposed to enhance the beam quality. An electron beam with velocity ratio of 1.20 and transverse velocity spread of 2.11% is obtained. The beam transportation stability with geometry misalignment is also analyzed, and the assembly accuracy should be controlled under 0.1 mm. The stray electron is intercepted by the capture structure to avoid the bombardment to the interaction circuit. Then the cathode is fabricated, and the temperature distribution is measured. The experimental result matches well with the simulation. The electron beam quality considering expansion, surface roughness, and thermal emission is estimated, and the total transverse velocity spread is about 2.63%. [ABSTRACT FROM AUTHOR]

In order to enhance the power capacity of gyro-traveling wave tube (Gyro-TWT), a novel multisectorial-tunnel circuit is presented in this article. The multisectorial tunnel could extend the transverse dimension of RF circuit for higher power electron beam transportation. The azimuthal drifting and transportation distortion performance for rotated electron beam are analyzed. A multibeam magnetron injection gun (MIG) is designed. The electron beam with pitch factor of 1.09 and axial velocity spread of 3.5% is obtained. And the designed cathode was fabricated and temperature distribution was measured. It provides a possible method to enhance the power capacity of Gyro-TWT. [ABSTRACT FROM AUTHOR]

In this paper, a novel triode-type magnetron injection gun (MIG) with three emitters designed for gyrotron traveling wave amplifiers has been presented. This MIG can be operated in Ku/Ka/Q single band or Ku-Ka/Ka-Q dual band. The optimization of the MIG is accomplished by a multiobjective genetic algorithm method. It is anticipated that this MIG possesses an axial velocity spread of <5% in all the operating frequency bands. The results of sensitivity study show that this MIG can work stably within reasonable parametric windows. Velocity spreads considering cathode surface roughness and initial thermal temperature are analyzed. Cathode configuration with heat insulation chambers is introduced to cut off the thermal flow among the emitters. Thermal analysis has been performed. [ABSTRACT FROM AUTHOR]

The magnetron injection gun (MIG) is an important component in the gyro-traveling wave tube (gyro-TWT). The electron velocity spread induced to the mismatch of the electric and magnetic fields influences the performance of gyro-TWT. To improve electron beam quality, we designed a modulating anode with curved geometry. And the multi-objective genetic algorithm was employed to optimize the curved geometry. An electron beam with a velocity ratio of 1.05 and low transverse velocity spread of 0.31% in a MIG for a Q-band gyro-TWT is obtained. Compared with the previous design with a transverse velocity spread of 1.17%, the electron beam performance got improved. And the thermal analysis and parametric sensitivity were done. The curved MIG can stably provide an electron beam with a transverse spread lower than 0.8%. [ABSTRACT FROM AUTHOR]