基于CAFE2装置实现超导射频腔热失超故障的自动化甄别及分类

Automated Detection and Classification of Superconducting Radio-frequency Cavity Quenching Faults Based on CAFE2

  • 摘要: 中国科学院近代物理研究所的连续波超导直线加速器CAFE2为超重元素的合成研究提供了重要的实验平台,其能可靠与稳定地运行是开展实验研究的根本保障。超导射频腔(超导腔)故障是加速器的主要故障来源,其中,腔体热失超易导致多腔集体宕机,是最具危害性的超导腔故障模式。热失超与多种其他故障模式(如氦压变化及Ponderomotive单调失稳)的射频信号波形非常相似,难以通过射频信号波形直接判别热失超现象。超导腔的有载品质因数(QL)在热失超时显著变化,QL的变化可作为判断热失超的重要依据。因此,本文基于腔体微分方程建立了动态QL的求解模型,以实现热失超故障的甄别,并在CAFE2装置验证了该模型的有效性。进一步研究发现,CAFE2装置上存在3种不同机制的热失超现象。本文结合专家特征与机器学习技术,成功实现了热失超现象的自动化分类,为超导腔故障的快速诊断提供了新方法。

     

    Abstract: With the rapid progress in superheavy element research in China, the continuous-wave superconducting heavy-ion accelerator CAFE2 has become a critical platform for superheavy element synthesis. As China’s first continuous-wave superconducting heavy-ion accelerator, CAFE2 is notable for its high energy output and operational stability. However, one of the primary challenges during its operation is the failure of superconducting radio-frequency (SRF) cavities. Among these, quenching represents the most serious failure mode, as it often results in simultaneous failure of multiple cavities, significantly impacting experimental outcomes. The similarity between quenching RF signal waveforms and other fault patterns makes accurate fault identification essential for ensuring the accelerator’s reliable performance. During quench events, the loaded quality factor (QL) of SRF cavities exhibits significant changes, which provides a key metric for detecting quenching. This study aims to develop a dynamic QL model based on the cavity’s differential equations, enabling efficient identification and classification of quenching events. Extensive experiments were conducted on the CAFE2 system at the Institute of Modern Physics, Chinese Academy of Sciences, and the model was validated by analyzing the operational data of SRF cavities. Our research revealed three distinct quenching mechanisms through the analysis of fault signals collected from the CAFE2 system, using the dynamic QL model. To further enhance fault recognition accuracy, a set of expert-derived features and applied machine learning techniques were designed to automate the classification of these quenching mechanisms. By constructing a random forest classification model, high-precision classification of the various quenching types was achieved and the efficiency of fault diagnosis was greatly improved. Real-time RF signal collection from SRF cavities was involved in our methodology, focusing on key features such as cavity pressure, forward power, and reflected power. These signals were processed using the dynamic QL model to identify characteristic QL changes indicative of quenching. Additionally, large-scale fault data analysis enabled us to differentiate quenching from non-quenching events, reducing false positives and enhancing the accelerator’s operational safety. The results demonstrate that the dynamic QL model is effective in accurately detecting and classifying SRF cavity quenching events. This work provides both theoretical insights and practical guidelines for the operation and maintenance of superconducting accelerators. By improving fault detection accuracy and informing operational strategies, our findings contribute to the continued advancement of superheavy element research. Moving forward, we aim to further refine the model and explore additional machine learning-based methods to address emerging challenges in accelerator operations.

     

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