大气贮存对激光刻蚀铜二次电子发射的影响

Influence of Atmospheric Storage on Secondary Electron Emission of Laser-Etched Copper

粒子加速器的工作性能受电子云效应的严重影响,二次电子产额(Secondary electron yield,SEY)是评判电子云效应的重要参数。利用激光刻蚀技术加工真空室内表面可以有效抑制真空室内二次电子发射,缓解电子云效应。无氧铜材料凭借其高电导率、高热导率和良好的辐射屏蔽性能成为建造新一代粒子加速器真空室的首选材料。由于粒子加速器真空室的建造周期长,在其制造、安装、调试过程中,刻蚀部件将不可避免地面临长期储存的问题。为研究大气贮存对刻蚀部件二次电子发射的影响,文章采用激光刻蚀技术对无氧铜材料进行表面处理,测试并分析刻蚀前后样品的表面特性与SEY。在样品贮存期间,定期对刻蚀样品进行SEY测试。结果表明,随着贮存时间的延长,刻蚀无氧铜的SEY逐渐升高。表面化学状态的变化是造成SEY上升的主要原因。文章将为未来加速器的真空室表面处理提供一种可行方法,为激光刻蚀部件的贮存方法提供实验支撑。

The operating performance of particle accelerators has been seriously affected by the electron cloud effect(e-cloud).The secondary electron yield(SEY)is one of the main factors for judging the e-cloud.The secondary electron emission(SEE)and the e-cloud can be effectively suppressed through laser-etching the inner surface of the vacuum chamber.Oxygen-free copper(OFC)has become the first choice for the vacuum chambers of modern accelerators due to its high electrical conductivity,high thermal conductivity,and effective radiation shielding properties.Due to the long construction period of the vacuum chambers in the particle accelerators,the laser-etched components will inevitably face the problem of long-term storage during their manufacturing,installation and commissioning.In this paper,the oxygen-free copper was treated by laser-etching technique,and the surface characterization and SEY were measured before and after laser-etching.The laser-etched samples were periodically measured for SEY during the two-year storage to study the influence of atmospheric storage on SEE.The results show that the SEY of the laser-etched OFC rises gradually as the storage time increases,which can be ascribed to the change in the surface chemical state.The paper aims to provide a feasible method for the surface treatment of vacuum chambers in modern accelerators and experimental support for the storage of laser-etched components.