用横向反馈系统对上海光源多束团不稳定性的诊断

Multi-bunch instability diagnostics via transverse feedback system in Shanghai Synchrotron Radiation Facility

在上海光源二期升级改造过程中,为了解和追踪由阻抗引起的多束团不稳定性变化以及升级后的横向反馈系统对这种不稳定性的抑制效果,在机器研究中利用新反馈处理器的诊断工具记录了束流不同状态下的横向运动过程,分析得到了最主要的横向多束团不稳定模式在束流稳态、注入瞬态以及增长-衰减过程中的变化情况,评估了横向反馈的作用效果,计算出该模式增长率/阻尼率以及增长率与束流的依赖关系。

For investigating and tracing the multi-bunch transverse coupled instability caused by beam impedance and evaluating the suppressive effect to the instability by the newly updated Transverse Feedback System during the upgrade process of Shanghai Synchrotron Radiation Facility(SSRF) PHASE Ⅱ, transverse beam motion in different states were recorded by diagnostics tool of feedback processor in the system, by which the evolution of dominate instability modes were analyzed respectively in steady-state, injection transient and growing-damping process. Growth/Damp rate as well as dependence of growth rate and beam current were calculated. Also, performance of the feedback system was evaluated. These research results provide data support for machine operation optimization.