环形加速器中,特别是强流正离子环形加速器中由于二次电子聚集而形成的电子云效应对高流强下的加速器运行会产生至关重要的影响.环形加速器中二次电子产生的主要原因在于初始电子在束流作用下获得能量,与束流真空管道内壁发生碰撞,如果此时真空室内壁材料的二次电子产额(Secondary Electron Yield,SEY)大于1,则会在束流管道内形成二次电子倍增而逐渐积累形成电子云.文章将结合国内近几年正离子环形加速器的设计建造参数(北京正负电子对撞机升级改造工程BEPCⅡ、中国散裂中子源快循环同步加速器CSNS/RCS及下一代环形正负电子对撞机计划CEPC),通过二次电子产生的物理机制分析、理论计算及仿真模拟对其产生、运动、聚集及平衡过程进行研究,探索二次电子发射系数对电子云密度的影响,进而提出降低环形加速器中电子云密度的方法.
The Influence of Secondary Electron Emission on Electron Cloud Density in Circular Accelerators
The electron cloud effect caused by secondary electrons accumulation in circular accelerators,es-pecially in high current positive particle accelerators,has crucial influence on the operation of accelerators with high beam intensity.The main reason for the generation of secondary electrons in a circular accelerator is that the initial electrons with acquired energy collide with the inner wall of the beam chamber.If the secondary electron yield of the wall material is greater than 1,secondary electrons are multiplied and accumulate in the ring to form an electron cloud.The research will focus on the design and construction parameters of positive particle circular accelerators in recent years in China(such as Beijing Electron Positron Collider Upgrade Project,BEPCⅡ;China Spallation Neutron Source,CSNS;and Circular Electron Positron Collider,CEPC),investigates the generation,movement,accumulation,and balance process of secondary electrons through physical mechanism analysis,the-oretical calculation,and simulation,explores the influence of secondary electron emission coefficient on electron cloud density,and then proposes methods to reduce electron cloud density in circular accelerators.
Electron cloudSecondary electronCircular acceleratorBEPCⅡCSNS
万方数据
维普
