From the beginning of the NSLS-II project, the vacuum chamber of the NSLS-II storage ring has been optimized to reduce its impedance. The optimization, performed in close collaboration with the Diagnostic, Vacuum, RF, and Mechanical Engineering groups, has been achieved via calculating the impedance of the vacuum chamber components with the use of both analytical and numerical tools, with the numerical computations carried out with the GdfidL code. For reliable NSLS-II operation with the total beam current of 500 mA, each component of the vacuum chamber has been individually optimized to minimize the beam-induced heating and to prevent single-bunch and coupled-bunch instabilities. In this article, the impedance calculation and optimization know-how are summarized for all the chamber components, and the total longitudinal impedance budget is analyzed. As a result of this extensive research and engineering effort, the design beam current of 500 mA has been recently accumulated in NSLS-II without any major problem caused by the collective effects.

从NSLS-II项目的开始，就对NSLS-II存储环的真空室进行了优化，以降低其阻抗。与诊断，真空，射频和机械工程部门密切合作进行的优化，是通过使用分析和数值工具计算真空室组件的阻抗来实现的，并且使用GdfidL代码。为了在总射束电流为500 mA的情况下可靠地进行NSLS-II操作，已对真空室的每个组件进行了单独优化，以最大程度地减少射束感应加热并防止单束和耦合束不稳定性。本文总结了所有腔室组件的阻抗计算和优化诀窍，并分析了总的纵向阻抗预算。由于这项广泛的研究和工程工作，最近在NSLS-II中累积了500 mA的设计束电流，而没有任何集体效应引起的重大问题。