Design of RF shielding CF flange copper ring structure

Zhao Feng; Zhu Xiaoxiao; Wei Wei; Chang Renchao; Zhang Hao; Lin Hanwen

doi:10.11884/HPLPB202537.250024

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Zhao Feng, Zhu Xiaoxiao, Wei Wei, et al. Design of RF shielding CF flange copper ring structure[J]. High Power Laser and Particle Beams. doi: 10.11884/HPLPB202537.250024

Citation:

Zhao Feng, Zhu Xiaoxiao, Wei Wei, et al. Design of RF shielding CF flange copper ring structure[J]. High Power Laser and Particle Beams. doi: 10.11884/HPLPB202537.250024

Zhao Feng, Zhu Xiaoxiao, Wei Wei, et al. Design of RF shielding CF flange copper ring structure[J]. High Power Laser and Particle Beams. doi: 10.11884/HPLPB202537.250024

Citation:

Zhao Feng, Zhu Xiaoxiao, Wei Wei, et al. Design of RF shielding CF flange copper ring structure[J]. High Power Laser and Particle Beams. doi: 10.11884/HPLPB202537.250024

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Design of RF shielding CF flange copper ring structure

doi: 10.11884/HPLPB202537.250024

Institute of Advanced Science Facilities, Shenzhen, 518107, China

Received Date: 2025-02-14
Accepted Date: 2025-07-16
Rev Recd Date: 2025-07-15

Available Online: 2025-08-21

Abstract

Abstract

Background
High-repetition-rate electron accelerators face beam instabilities induced by wake fields from beam-vacuum chamber interactions. Geometric discontinuities at ubiquitous Con Flat (CF) knife-edge flange connections are a dominant source of beam-induced impedance in all-metal vacuum chambers.
Purpose
To mitigate this impedance, this paper designs an RF-shielded flange-gasket connection structure achieving a smooth post-tightening transition at the interface, thereby minimizing impedance.
Methods
1. Electromagnetic Simulation: 3D simulations (CST) analyzed impedance effects of radial step heights and axial gaps at the transition, establishing allowable parameter ranges. 2. Deformation Simulation: ANSYS simulations modeled the shielded flange-copper gasket assembly to preliminarily determine inner diameter specifications for various gasket models. 3. Vacuum Sealing Tests: Verified ultra-high vacuum integrity under applied tightening torque. 4. Transition Geometry Testing: Measured the achieved radial step and axial gap post-tightening to define optimal copper gasket dimensions and tightening torque. 5. Comparative Simulation: CST simulations compared power loss and impedance for smooth chambers, standard flange-gasket transitions, and the proposed shielded transition.
Results
1. Electromagnetic simulations defined critical tolerance ranges for radial step and axial gap. 2. Deformation simulations provided initial gasket inner diameter specifications. 3. Vacuum tests confirmed effective sealing at a tightening torque≥6 N·m. 4. Transition testing established the optimal tightening torque and key copper gasket dimensions ensuring minimal geometric discontinuity. 5. Comparative simulations demonstrated that the RF-shielded flange-gasket transition significantly reduces power loss and impedance compared to a standard CF transition, achieving performance close to that of a smooth vacuum chamber.
Conclusions
The designed RF-shielded flange-gasket connection structure effectively minimizes geometric discontinuity at the joint. Through combined electromagnetic, mechanical, and vacuum testing, critical parameters (radial step, axial gap, gasket dimensions, tightening torque≥6 N · m) were optimized. Electromagnetic verification confirms this design provides effective impedance shielding, offering a solution to mitigate wake-field-induced instabilities at flange connections in high-energy accelerators.
- Electron accelerator,
- High repetition rate,
- Wakefield,
- beam coupling impedance,
- RF shielding

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References(21)

References

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