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arXiv · 2407.01609

Radio-frequency cavity field measurements through free falling bead

Xiaonan Du·Lars Groening
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Abstract

This paper introduces a novel bead-falling measurement method for the precise and efficient mapping of electromagnetic fields within radio-frequency (RF) cavities, which are crucial components in the design of accelerators. The traditional bead-pull method, while effective, involves mechanical complexities and is prone to errors from wire perturbations. The innovative method reported here leverages the simplicity and accuracy of free-falling beads to mitigate these issues. This technique eliminates the need for a wire-pulley system, thereby simplifying the experimental setup and reducing potential mechanical errors. We detail the development and operational principles of this new method, including the design of a compact, portable measurement device that integrates a bead/droplet release system and a bead detection system linked to a Vector Network Analyzer (VNA). The device has been tested with a three-gap buncher cavity and a scaled Alvarez-type cavity, demonstrating its ability to perform rapid, reliable field measurements under various challenging conditions, including low signal-to-noise ratios and environmental vibrations. The results confirm the method's superiority in precision and operational efficiency, potentially setting a new standard for RF cavity diagnostics and tuning.

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Xiaonan Du, Lars Groening. 2024-06-27. Radio-frequency cavity field measurements through free falling bead. https://arxiv.org/abs/2407.01609

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