BEPC储存环真空系统

Vacuum System of BEPC Storage Ring

本文描述了ＢＥＰＣ储存环真空系统的设计、制造和运行。为了使储存环中正负电子的寿命达到８—１０小时，要求真空系统的动态压强低于３×１０－９Ｔｏｒｒ。储存环真空系统的主要气载是由同步辐射光与真空盒壁相互作用产生的。由于弯转的铝真空盒具有容易加工、高的热导性和低的放气率等特性，被广泛应用于真空系统。１１０Ｌ／ｓ的涡轮分子泵机组把系统预抽到１０—６Ｔｏｒｒ左右，主抽泵是工作在弯转磁场中的分布式溅射离子泵。５００Ｌ／ｓ的溅射离子泵安装在特殊的部位，如高频腔，静电分离器以及物理实验区等．１００Ｌ／ｓ离子泵每隔６．５米安装一台，当分市泵不工作时用来维持系统真空．八个全金属闸板阀把真空系统分成八个部份。为了减少由于高次模造成的束流能量损失，要求真空系统光滑过渡。

Abstract The design,fabrication and operation of BEPC storage ring vacuum systemare described. Storage ring requires a pressure lower thap- 3X 10-9 torr toobtain a beam lifetime of 8-10 hours.The main gas load of vacuum system isproduced by interaction of synchrotron radiation with the chamber wall.Extruded aluminium chamber has been used for easy fabrication,high thermalconductivity and low outgassing rate etc. Roughing down to approximately10-6 torr is achieved by 110L/s turbomolecular pump groups.The main pumpingis preferably achieved with distributed sputter ion pumps working in thefield of the bending magnets.500L/s sputter ion pump are provided for specialsection such as radio frequency cavity, electrostatic separator and physicsexperiment regions,100L/s sputter ion pumps are connected to vacuum systemto keep a better vacuum at about 6.47m intervals while distributed sputter ionpumps don't operate.The 240.4m of the vacuum system are subdivided into 3sectors by means of all metal full aperture gate valves. The high bunchcurrents of stored electrons require additionally a 'smooth' vacuum systemwithout step, in order to reduce energy losseR due to rf parasitic modesexcition.