Operation Performance Evaluation of Accelerator Basedon Cluster Analysis of Bunch-by-bunch Diagnostic Data
YANG XING1,3, LENG YONGBIN2,*, ZHOU YIMEI4
1. Shanghai Institute of applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
2. University of Science and Technology of China, Anhui 230026, China;
3. University of Chinese Academy of Sciences, Beijing 100049, China;
4.Shanghai Advanced Research Institue, Chinese Academy of Sciences, Shanghai 200120, China

Introduction

HOTCAP

In order to improve the operating performance of theparticle accelerator, it is better to develop a toolkits tomonitor and analyze the sub-health state of the facility
in addition to ensuring the stability of basic parameters.
such asThe 3D bunch-by-bunch position measurement system
combined with cluster analysis is a feasible solution forthis requirement.
• beam current•

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lifetimetransverse size
longitudinal lengthtransverse postion
longitudinal phase

Algorithm
Normalize the features of every sample into a vector
space, compute the distances between them and thenclassify them based on their proximity is thefundamental principle of clustering analysis.
Sample can be classified based on the distance between
it and the center of the cluster, or they can be grouped
into the same cluster if the distance between them isless than a certain threshold.
This approach corresponds tothe K-means and the DBSCAN
algorithm respectively.

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Features••

Equilibrium Phase RF frequency•

SA or FA data indicates the long-term operation
status of the equipment.
Evaluating the short-term or even transient operating
status of a device requires turn-by-turn or evenbunch-by-bunch variation data.
We abstract the bunch-by-bunch data provided by
HOTCAP into a feature that describes the short-term
state of the device.
We abstract the transient changes in the lateral
operating point caused by injection into features thatdescribe the state of the injection system.
Refilled
Charge Phase Transverse tune•

• A software package to be used in high-speed oscilloscopebased three-dimensional bunch-by-bunch charge andposition measurement is presented.
• It offers many additional features such as injection
analysis, bunch response function reconstruction, andturn-by-turn beam analysis.
• The software package has an easy-to-understand graphicaluser interface and convenient interactive operation, which
has been verified on the Windows 10 system.

Analysis
Collect steady-state operation data on different days,
extract the equilibrium phase and perform cluster
analysis along with the feature of fill pattern.
• X is the feature offill pattern, which
represents theuniformity of charge
filling between
bunches.
• Y in up represents
the dispersion ofequilibrium phases. Yin bottom represents
the slope ofequilibrium phases.
• Collect injection dataon different days.
• The longitudinalmotion of refilledcharge can beabstracted as threefeatures: vibration
amplitude, vibration
frequency, and decaytime.

Conclusion• Cluster analysis can be used to evaluate the operation
performance using the bunch-by-bunch diagnostic data.
• In SSRF storage ring, the relationship between theequilibrium phase and the filling pattern can be clusteredin two different states.
• There are three different states in which the injection
system is matched to the storage ring.

References[1] https://scikit-learn.org/1.2/[2] Xu X Y, Leng Y B, Gao B, et al. HOTCAP: a new software package for high-speed oscilloscope-based threedimensional bunch charge and position measurement[J]. Nuclear Science and Techniques, 2021, 32: 1-11.

Contact Email: lengyb@ustc.edu.cn