强流重离子加速器束内不稳定性测量及分析方法研究

With the increase of beam intensity for the physics experiment offered by the accelerator, especially the increase of particle number in single bunch, intra-bunch instability has become the primary factor to determine whether the heavy ion accelerator can operate in high intensity and high power state or not, which can induce the beam emittance increase, beam lifetime decay and fast beam loss. Therefore, the studies on the quickly and exactly measurement and suppression of intra-bunch instability must be carried on. This project will study the factors causing the intra-bunch instability based on the simulated results, and design the measurement and analysis method of the intra-bunch instability,then implement the data acquisition and processing algorithm based on FPGA for this system. New experiment measurement system will be established in the HIRFL-CSRm to verify the measurement and analysis method. The beam instability measured by this system will be reviewed with the simulation results. Those research results will provide important analysis basis for the further implementation of beam interlock and feedback control, and important theory basis and design reference for the high intensity and high energy heavy ion accelerator facility in the future.

随着物理实验要求加速器提供的束流流强的提高，尤其是单束团内离子数的增加，束内不稳定性已成为决定重离子加速器能否高功率、高流强运行的关键因素，这种不稳定性导致束流发射度增长速率快，寿命下降，损失加剧。因此，快速准确的判断束内不稳定性并进行抑制将是保障重离子加速器高效稳定运行进而满足物理实验需求的亟待开展的工作。本项目拟基于束内不稳定性的先期模拟结果，探寻并开展重离子束流束内不稳定性的测量方法，设计束团内不稳定性的测量方案；编写基于FPGA的束流信号采集和处理算法；以HIRFL-CSRm为依托平台搭建测试系统，实现束内不稳定性测量及分析研究，进行束内离子运动轨迹的测量与模拟计算结果的相互验证；研究结果将为实现束内不稳定性抑制及反馈提供分析基础，为今后建设的高能强流重离子加速器提供重要的理论依据和设计经验。

本项目基于对强流重离子束内不稳定性的调研结果，开展了束流位置计算和测量方法研究；研制了束流位置探测器（BPM）测量所需的前端放大器和电子学系统。搭建了基于实验室的BPM标定平台，开展了基于HIRFL-CSR装置和HIMM同步加速器的在束测试。提出了一种新的束流逐束团位置测量方法；实现了基于MATLAB的束团检测、滤波算法和位置计算的仿真，实现了FPGA算法移植；并成功应用于HIMM的位置测量和闭轨测量前期设计工作中，为今后建设的同步轨加速器闭测量实现、束流稳定性分析提供了重要的理论依据和设计参考经验。