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Ferrite-SiC axially graded absorber for broadband higher-order mode damping and thermal response in a 1.5 GHz TM020-mode cavity

Ziyang Xu1,2,*, Zhongquan Li1,2,*, Zhejia Xu1,2, Kuangkuang Ye1,2, Yuanli Luo1,2, and Xuerui Hao3,4,†

  • *These authors contributed equally to this work.
  • †Contact author: xrhao@ihep.ac.cn
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Phys. Rev. Accel. Beams 29, 103804 – Published 28 October, 2026

DOI: https://doi.org/10.1103/bp2m-nwm7

Abstract

The magnetic-field node of a TM020-mode cavity permits compact higher-order-mode (HOM) damping, but displacement of the coupling slots can expose the absorber to appreciable accelerating-mode leakage. A ferrite-SiC absorber is investigated numerically to combine broadband damping with improved thermomechanical response in a 1.5 GHz cavity. A transmission-line formulation relates material ordering to input impedance, and coaxial full-wave calculations show that placing SiC ahead of ferrite suppresses the pronounced low-frequency absorption dip of the reverse arrangement. The concept is integrated into a radially folded, six-sector absorber, with parameter sweeps resolving the effects of material dimensions, slot height, and sector angle. For the six higher-order modes (HOMs) tabulated, external quality factors are below 150, while the aligned accelerating mode has an external quality factor of 1.20×107. Frequency-resolved loss maps show increasing SiC participation across the transition near 2 GHz. At the same imposed absorber load of 2.65 kW, the hybrid reduces peak temperature rise from 97.0 to 79.9 K and maximum first principal stress in ferrite from 146.0 to 78.6 MPa, reductions of 17.6% and 46.2%, respectively. These results connect electromagnetic loss redistribution to improved thermal and mechanical response and support the hybrid arrangement as a compact damping option for TM020-mode cavities.

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Phys. Rev. Accel. Beams 29, 103804– Published 28 October, 2026
  • Received 10 April 2026
  • Accepted 9 October 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

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