中文摘要：

BEPCⅡ是BEPC的升级工程，它被设计工作在亮度为1×10^33cm^-2·s^-1的τ-charm能区．根据用几个不同的程序进行的束一束相互作用的模拟结果，BEPCⅡ的亮度较设计亮度有不同程度的下降．其中一个程序的计算结果表明，在原设计对撞模式下运行，BEPCⅡ的运行亮度只能达到0．50×10^33cm^-2·s^-1．为了提高BEPCⅡ的运行亮度，研究了小动量压缩因子的对撞模式，亮度可以提高到0．54×10^33cm^-2·s^-1．相应的束长由1．5cm减小到1．2cm．为了和1．2cm的束长相匹配，又研究了对撞点垂直β函数等于1．2cm的对撞模式．根据束一束相互作用的模拟结果，选择了几个高亮度的工作点，对它们的线性lattice和动力学孔径等进行了研究和优化．其中，最高的亮度可以达到0．828×10^33cm^-2·s^-1．

英文摘要：

BEPC Ⅱ, the upgrading project of the Beijing Electron-Positron Collider （BEPC）, has been designed with a luminosity of 10^33cm^-2·s^-1 at the τ-charm energy region. According to the beam-beam simulation results, the luminosity of BEPCⅡ with a crossing collision angle of 11mrad is about 0.50×10^33cm^-2·s^-1 with the original operation mode at the working point of 6.53/5.58. To increase the operating luminosity of the BEPCⅡ, a low momentum compaction factor （αp） collision mode has been studied which can increase the luminosity to 0.54×10^33cm^-2·s^-1. If the bunch length of the low αp mode is reduced from 1.5cm to 1.2cm, a mode with vertical beta function at IP equal to 1.2cm could push the luminosity to 0.828×10^33cm^-2·s^-1 at the working points 6.53/5.56.