16–21 Aug 2026
Daejeon Convention Center
Asia/Seoul timezone

Feed-down-Based Evaluation of Shaft Deflection in the PAL PCB Rotating Coil System for XFEL Quadrupole Measurements

THPO092
20 Aug 2026, 16:00
2h
1F Exhibition Hall (Daejeon Convention Center)

1F Exhibition Hall

Daejeon Convention Center

Poster Presentation MC4.A05: Other technology THPO - Poster Session

Speaker

Yoon Geol Choi (Pohang Accelerator Laboratory)

Description

PCB-based rotating coil system has been developed at Pohang Accelerator Laboratory (PAL) for high-precision magnetic measurements of XFEL quadrupole magnets. Since the rotating coil is supported by a long ceramic shaft, shaft sagging can shift the coil center from the magnetic center, introducing systematic errors in multipole analysis through the quadrupole feed-down effect. In this work, a feed-down-based method was developed to quantitatively evaluate shaft deflection using a Permanent Magnet Quadrupole (PMQ). The proposed method was first validated by translating the rotating axis by 100 μm in both horizontal and vertical directions, yielding calculated displacements of 100.64 μm and 100.02 μm, respectively, while the quadrupole component remained constant within 10-4. The shaft deflection profile was then reconstructed from the measured A1​/C2​ ratio at nine longitudinal positions. The maximum shaft sagging was approximately 46 μm, confirming that the ceramic shaft satisfies the required mechanical tolerance. The proposed method provides a simple and reliable approach for evaluating shaft deflection and coil-center alignment in high-precision rotating coil measurement systems.

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Author

Yoon Geol Choi (Pohang Accelerator Laboratory)

Co-authors

Beom Jun Kim (Pohang Accelerator Laboratory) Dong Eon Kim (Pohang Accelerator Laboratory) Min-Jae Kim (Pohang Accelerator Laboratory) YoungGyu Jung (Pohang Accelerator Laboratory)

Presentation materials

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