Exploration of a PBG-based cavity structure for a multiple-beam extended interaction klystron

Abstract

The feasibility of a photonic band-gap (PBG)-based interaction structure was analytically explored for a multiple-beam extended interaction klystron amplifier. This configuration accrues the advantages of the multiple-defect PBG-based extended interaction structure and multiple-beam operation. The mode configurations were analysed through 3D electromagnetic simulation and the applicability of the photonic band-gap cavity was studied for the multiple-beam operation of an extended interaction klystron amplifier. A typical six-defect cavity operating at around 83 GHz was designed for electron–wave interaction at 2π mode with 6 electron beams each carrying 300 mA current at the accelerating potential of 16.5 kV. A particle-in-cell simulation shows that an output power of ∼2 kW is possible with electronic efficiency of around 6.7%. A frequency-scaled-down interaction structure at Ku-band was fabricated and cold measurements were carried out to ascertain the feasibility. The measured values of the frequency for various modes, loaded quality factor and 3 dB bandwidth were found to be within 0.36%, 5.3% and 4.07%, respectively, against those from the simulation.

KEYWORDS:

• Extended interaction klystron
• multiple-beam klystron
• photonic band-gap (PBG) cavity structure

Acknowledgements

The authors are thankful to the Centre Head, MTRDC for the permission to publish this work. Thanks are also due to Dr. Ashok Bansiwal and Dr. M. Sumathy for the many valuable suggestions and to Shri Y. Muralidhar for support in assembling the experimental cavity and measurement.

Disclosure statement

No potential conflict of interest was reported by the author(s).