等效电路算法在 CSNS-II 椭球超导腔预调谐中的应用研究

Application of equivalent circuit algorithm in pre-tuning of CSNS-II ellipsoidal superconducting cavities

摘要

提出了一种基于等效电路模型的快速预调谐方法，可应用于 CSNS-II 工程中的多单元椭球超导腔上。通过分析椭球超导腔的电磁特性，建立了等效电路模型，将电磁问题简化为电感、电容及耦合电容的电路问题，推导了电场平坦度调谐过程中各单元频率调谐量的计算方法。通过仿真分析表明，该算法使腔体电场平坦度由 77% 提高到 98% 以上。基于该算法，设计了一套集成高频参数测量与机械调谐的预调谐系统。使用铜材椭球样腔进行实验，经过多次迭代调谐后，电场平坦度达到 96.5%，满足 CSNS-II 超导腔预调谐性能要求。该研究为多单元超导腔的高精度预调谐提供了理论与工程上的参考解决方案，对提升粒子加速器性能具有重要应用价值。

Abstract

A rapid pre-tuning method based on an equivalent circuit model is proposed for multi-cell elliptical superconducting cavities in the CSNS-II project. Through electromagnetic analysis of elliptical superconducting cavities, an equivalent circuit model was established by decomposing the electromagnetic problem into circuit problem including inductance, intrinsic capacitance, and inter-cell coupling capacitance. A computational method was derived for quantifying frequency tuning requirements during electric field flatness optimization. Simulation results indicate that the cavity’s electric field flatness has been improved from 77% to over 98% after tuning. Based on this method, a pre-tuning system integrating high-frequency parameter measurement and mechanical tuning was designed. The experiment was conducted using a copper elliptical prototype cavity. After multiple iterations of tuning, the flatness of the electric field reached 96.5%, meeting the pre-tuning specifications of the CSNS-II superconducting cavity. This study provides a theoretical and engineering solution for high-precision pre-tuning of multi-cell superconducting cavities, showing significant application value for enhancing the performance of particle accelerators.

关键词

超导腔 / 预调谐 / 等效电路模型 / 调谐算法

Key words

superconducting cavity / pre-tuning / equivalent circuit model / tuning algorithm

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基金资助

广东省基础与应用基础研究基金(2020A1515110579)