高动态磁场环境下陶瓷真空盒耦合阻抗的数值模拟

黄良生; 吴彬; 黄明阳; 刘仁洪; 谭彪; 王鹏程; 李晓

doi:10.11884/HPLPB202638.250137

高动态磁场环境下陶瓷真空盒耦合阻抗的数值模拟

doi: 10.11884/HPLPB202638.250137

黄良生^{1, 2,},
吴彬^{1, 2},
黄明阳^{1, 2},
刘仁洪^{1, 2},
谭彪^{1, 2},
王鹏程^{1, 2},
李晓^{1, 2}

1.
中国科学院高能物理研究所，北京 100049
2.
散裂中子源科学中心，广东东莞 523803

基金项目: 广东省自然科学基金项目(2021B1515140007)

详细信息

作者简介:
黄良生，huangls@ihep.ac.cn

中图分类号: O44,O57
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- 文章访问数: 26
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- 被引次数: 0
出版历程
- 收稿日期: 2025-05-16
- 修回日期: 2025-12-12
- 录用日期: 2025-12-08
- 网络出版日期: 2025-12-15

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

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

摘要

摘要: 在快循环同步加速器（RCS）中，磁场与束流能量保持同步，形成高动态的磁场环境。为完全避免涡流效应并降低阻抗，RCS通常使用陶瓷真空盒，并覆盖复杂的屏蔽层结构。虽然传统理论认为此类结构的实部阻抗对束流动力学的影响可以忽略，但中国散裂中子源（CSNS）的阻抗测量却揭示了陶瓷真空盒中存在低频谐振阻抗。理论溯源表明，这一阻抗正是导致CSNS/RCS束流不稳定性的关键机制。由于该谐振阻抗的物理机制复杂，尚无独立方法验证测量阻抗。为此，本研究首次采用数值模拟方法证实了谐振阻抗的客观存在，并通过系统模拟涵盖了RCS各类陶瓷真空盒的构型，成功构建了高精度阻抗模型，为强流加速器中的束流不稳定性研究提供了重要的理论支持。
- 阻抗 /
- 陶瓷真空盒 /
- 屏蔽 /
- 共振 /
- 高动态磁场
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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图 1 陶瓷真空盒结构示意图

Figure 1. Illustration of the ceramic chamber

下载: 全尺寸图片幻灯片

图 2 环路法阻抗测量原理图

Figure 2. Schematic setup of the transverse impedance measurement with one loop method

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图 3 陶瓷真空盒实验室阻抗测量布局图

Figure 3. Layout diagram on the bench

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图 4 INB1陶瓷真空盒横向阻抗测量结果

Figure 4. Measured transverse impedance of INB1

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图 5 INB1陶瓷真空盒CST模拟模型

Figure 5. CST simulated model of the ceramic chamber

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图 6 RCS陶瓷真空盒阻抗

Figure 6. Impedance of ceramic chambers within the RCS

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表 1 RCS陶瓷真空盒参数表

Table 1. Parameters of the RCS Ceramic Chamber

name	shape	length/m	radius^a/mm	thickness^b/mm	number
MB	elliptic	66.6	218×135	15×8.5	24
QA	circular	12.4	91.5	7.5	16
QB	circular	24.6	124.5	7.5	16
QC	circular	12.3	99.5	7.5	8
QD	circular	9.2	115	7.5	8
INB^c	circular	4.4	80	7.5	4
Note：^a It means horizontal × vertical size for MB with an elliptic cross-section; ^b It means horizontal × vertical thickness for MB with an elliptic cross-section; ^b There are two similar types of injection chambers, and simplifies as one here.

下载: 导出CSV

表 2 INB1陶瓷真空盒谐振阻抗模拟和测量阻抗比较

Table 2. Simulated and measured resonant impedance of the INB1

	resontant freq/MHz	R_s/(kΩ/m)	Q
Simulation	0.123	450	150
Measurement	0.123	290	40

下载: 导出CSV

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