Machine learning based image processing technology application in bunch longitudinal phase information extraction

Xingyi Xu,Yimei Zhou,Yongbin Leng

doi:10.1103/physrevaccelbeams.23.032805

Abstract

We report on the application of machine learning (ML) methods to extract longitudinal phase information such as parameters of the synchrotron damping oscillation. Parameters of the synchrotron damping oscillation are important for the evaluation of machine status and bunch stability. It is of concern to extract these parameters with high-speed and high-precision. The previous methods, such as multiparameter nonlinear fitting and table look-up, are slower and easily fall into local optimal solutions. Our approach based on ML-image processing consists of training a virtual diagnostic to predict parameters using the beam position monitor (BPM) electrical signal data as inputs. We find that when the noise of data is large, our ML-model can still get better results than other methods, an important step toward on-line multiparameter extraction from multidimensional raw data.

Highlights

The injection transient process is a good starting point to study the beam instabilities since it occurs frequently in top-off mode
The data collected by beam position monitors (BPMs) is a combination of the stored charge, refilled
Recently we developed a method based on machine learning image processing technology to solve these problems

Summary

Introduction

The injection transient process is a good starting point to study the beam instabilities since it occurs frequently in top-off mode. The study of the injection transient is helpful for optimizing the state parameters of the injector and understanding the physical process of the merging of the stored charge and the refilled charge during the injection process [1,2,3,4]. Starting from 2012, the BI (beam instrument) group of SSRF (Shanghai Synchrotron Radiation Facility) performs bunch-by-bunch phase measurement and study the injection transient [5]. The refilled bunch contains the stored charge, refilled charge, and the crosstalks from other stored bunches. The stored bunch contains the stored charge and the crosstalks. If we get the turn-by-turn longitudinal phase of the refilled charge, the synchrotron damping oscillation can be monitored. The data collected by beam position monitors (BPMs) is a combination of the stored charge, refilled

Objectives

Methods

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Conclusion