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Radio-frequency design and commissioning of a flexible waveguide for high-vacuum S-band applications



Flexible waveguides, which allow for greater deformation as compared to traditional hard waveguides, are highly useful for simplifying waveguide system assemblies. However, the peak powers of these waveguides have been limited to several megawatts in non-vacuum environments. Herein, a novel flexible waveguide was developed for the S-band (2856 MHz) with the aim of facilitating the interconnection of two hard waveguides.


The flexible waveguide was composed of brass, and its surface was plated with oxygen-free high-conductivity copper for brazing with stainless steel flanges in a vacuum furnace. By connecting the stainless steel flanges together, it can be applied to a high-vacuum environment.


The prototype exhibited good measurement results in low-power microwave tests; the results of a 72-h vacuum leak test showed satisfactory vacuum performance as well, and no obvious surface collapse was observed. High-power microwave commissioning was conducted between June and July 2019; the waveguide showed a maximum average power of approximately 2.7 kW.


Unfortunately, the prototype was damaged after reaching that power level, which indicates the need for further optimization of the fabrication process. From our experiment, it is clear that the flexible waveguide cannot be used in large accelerators because of its average power limit.

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  1. T.R. Edgecock, N. Turner, R. Yogi, A. Sunesson, P. Aden, D. Naeem, R. Smith, The RF distribution system for the ESS, in Proceedings of IPAC2017, pp. 4352–4254 (2017)

  2. P. Shrivastava, J. Mulchandani, Y. Wahnmode, P. Mohania, Performance of 6 MW peak, 25 kW average power microwave system for 10 MeV, 10 kW electron linac, in Proceedings of APAC 2007, pp. 649–651 (2007)

  3. S. Smith, S. Hoobler, R.G. Johnson, T. Straumann, A. Young, R.M. Lill, L.H. Morrison, E. Norum, N. Sereno, G.J. Waldschmidt, D. Walters, LCLS cavity beam position monitors, in Proceedings of DIPAC 2009, pp. 285–287 (2009)

  4. P. Shrivastava, Y.D. Wanmode, D. Baxy, P.R. Hannurkar, An S-band microwave system for a 12 MeV microtron for medical applications, in Proceedings of APAC 2001, pp. 834–836 (2001)

  5. M. Uesaka, K. Demachi, K. Dobashi, T. Fujiwara, H.F. Jin, M. Jin, H. Zhu, J. Kusano, N. Nakamura, M. Yamamoto, E. Tanabe, Y. Hattori, I. Miura, Applications of X-band 950 KeV and 3.95 MeV linac X-ray source for onsite inspection, in Proceedings of IPAC2012, pp. 4071–4073 (2012)

  6. X. He, C. Meng, S.L. Pei, J. Lei, B.L. Deng, Development of flexible waveguide for high power high vacuum applications, in Proceedings of IPAC2019, pp. 2909–2911 (2019)

  7. X. He, J. Lei, J.R. Zhang, Development of a high-power high-directivity directional coupler and four power dividers for S-band, in Proceedings of IPAC2018, pp. 2422–2424 (2018)

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We would like to give our sincere thanks to all the colleagues who assisted in the process of developing and testing the flexible waveguide from design to high-power microwave commissioning, including but not limited to J. Lei, J.R. Zhang, D. Dong, X.C. Kong, Q. Le, Y.C. Liu, and R. Wang, as well as the entire team of our linac group and the accelerator department. We would also like to thank Editage ( for English language editing.


Funded by Youth Innovation Promotion Association CAS (2020015).

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Correspondence to Xiang He.

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He, X., Cao, JS., Deng, BL. et al. Radio-frequency design and commissioning of a flexible waveguide for high-vacuum S-band applications. Radiat Detect Technol Methods 4, 250–254 (2020).

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  • S-band
  • Flexible waveguide
  • High vacuum
  • Microwave commissioning


  • 29.20.-c