Numerical simulation of beam coupling impedance of ceramic chamber in dynamic magnetic field

Huang Liangsheng; Wu Bin; Huang Mingyang; Liu Renhong; Tan Biao; Wang Pengcheng; Li Xiao

doi:10.11884/HPLPB202638.250137

Volume 38 Issue 1

Dec. 2025

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Huang Liangsheng, Wu Bin, Huang Mingyang, et al. Numerical simulation of beam coupling impedance of ceramic chamber in dynamic magnetic field[J]. High Power Laser and Particle Beams, 2026, 38: 014002. doi: 10.11884/HPLPB202638.250137

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Huang Liangsheng, Wu Bin, Huang Mingyang, et al. Numerical simulation of beam coupling impedance of ceramic chamber in dynamic magnetic field[J]. High Power Laser and Particle Beams, 2026, 38: 014002. doi: 10.11884/HPLPB202638.250137

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Numerical simulation of beam coupling impedance of ceramic chamber in dynamic magnetic field

doi: 10.11884/HPLPB202638.250137

Huang Liangsheng^{1, 2
,},
Wu Bin^{1, 2},
Huang Mingyang^{1, 2},
Liu Renhong^{1, 2},
Tan Biao^{1, 2},
Wang Pengcheng^{1, 2},
Li Xiao^{1, 2}

1.
Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
2.
Spallation Neutron Source Science Center, Dongguan 523803, China

Received Date: 2025-05-16
Accepted Date: 2025-12-18
Rev Recd Date: 2025-12-12

Available Online: 2025-12-15

Publish Date: 2025-12-18

Abstract

Abstract

Background
The rapid cycling synchrotron (RCS) requires the magnetic field to track the energy ramp, producing a strongly time-dependent magnetic environment. To control beam coupling impedance and suppress field leakage, an RCS typically uses ceramic vacuum chambers covered in an RF shielding layer. The shield consists of parallel metal strips aligned with the beam and terminated by capacitors at either end, which preserves a low beam impedance while suppressing eddy currents induced by the time-dependent magnetic field. Previous theoretical studies suggest that the impedance of such a structure has a negligible impact on the beam. However, impedance measurements of the China Spallation Neutron Source RCS ceramic chamber have revealed the presence of a transverse resonant impedance.
Purpose
As this observation has not been verified by independent methods.
Methods
The CST electromagnetic simulations are used to test its presence.
Results
A high-fidelity simulation model has been developed and benchmarked against measurements, showing close agreement with the measured impedance.
Conclusions
The comparison confirms the validity of the impedance characterization. Simulations spanning six ceramic-chamber geometries are then used to construct a comprehensive impedance model for the RCS, which provides a foundation for subsequent studies of beam dynamics and collective effects.
- beam coupling impedance,
- ceramic chamber,
- RF shield,
- resonance,
- high dynamic magnetic environment

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References(18)

References

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