Xiaotong Guan

Design and Experiment of a 220/420-GHz Gyrotron for Nondestructive Evaluation

We report the design and experiment of a 220/420-GHz gyrotron oscillator for nondestructive evaluation which operates at the fundamental near 220 GHz and the second harmonic near 420 GHz of the electron cyclotron resonance frequency. Through optimizing electron gun for both operation modes, the TE26 mode at 423.1 GHz and the TE03 mode at 221 GHz are observed at output powers up to 8 and 6 kW, respectively, by only changing the beam voltage at a magnetic field of 8.2 T. The experimental results are in reasonable agreement with the design and simulation. In addition, the measurements of potential operation modes with peak output power are also presented in this paper.

High harmonic terahertz confocal gyrotron with nonuniform electron beam

The harmonic confocal gyrotron with nonuniform electron beam is proposed in this paper in order to develop compact and high power terahertz radiation source. A 0.56 THz third harmonic confocal gyrotron with a dual arc section nonuniform electron beam has been designed and investigated. The studies show that confocal cavity has extremely low mode density, and has great advantage to operate at high harmonic. Nonuniform electron beam is an approach to improve output power and interaction efficiency of confocal gyrotron. A dual arc beam magnetron injection gun for designed confocal gyrotron has been developed and presented in this paper.

Design of a 220-GHz continuous frequency-tunable gyrotron with quasi-optical cavity

The design of a 220 GHz continuous frequency-tunable gyrotron with a three-section tapered quasi-optical cavity is presented. The HE06 mode in quasi-optical cavity is selected as the operating mode. The tuning is achieved by changing the distance between the two mirrors, which ensures continuous variations in eigenfrequencies of the cavity. The PIC simulation results demonstrate the possibility of tuning the oscillation frequency by 8 GHz near 220 GHz (within a frequency band of about 3.6%) with an output power no less than 5 kilowatts.

Design of a magnetron injection gun with low velocity spread for 0.56THz third harmonic gyrotron

In this paper, the design of a double-anode magnetron injection gun for a 0.56THz third harmonic gyrotron is presented. Simulation predicts that a high quality electron beam is generated with parallel velocity spread of 2.19%, perpendicular velocity spread of 1.0%, and velocity pitch spread of 3.18% at α=1.5. The variations of velocity spread due to operation parameters are also presented.