An effective method to increase bandwidth of EIK at 0.34 THz

ABSTRACT

To increase the bandwidth of Extended Interaction Klystron (EIK) at 0.34 THz, the method of staggered tuning on cavities’ configurations is proposed. Based on the analysis of phase relationship between gap voltage and the bunched beam, the buncher cavities in EIK are reasonably staggered-tuned to achieve various resonance frequencies, which is helpful to flat the gain response of the whole device. The characteristics of output cavities with different numbers of gaps are then researched and the issue of start current for the self-oscillation mode is also involved, leading to the optimum number of gaps to enhance the interaction and avoid the instability. By comparing the performances of various typical stagger-tuned models, the final configuration is accordingly confirmed. Particle-in-cell simulation is eventually applied to study performance of the optimised structure, whose gain is 34.8 dB in peak and −3 dB bandwidth reaches about 500 MHz, which is double that of the synchronous-tuned structure.

KEYWORDS:

• Extended interaction klystron (EIK)
• bunched beam
• stability
• bandwidth
• particle-in-cell (PIC)

Acknowledgement

The authors wish to thank Prof. Yi Huang and Dr. Jiafeng Zhou from the University of Liverpool for valuable discussions and assistance.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China under Grant No. 61231003.