BEPCII Injector Linac Upgrade and Beam Instabilities

The upgrade project of the Beijing Electron Positron Collider (BEPCII) and its injector linac is working well. The linac upgrade aims at a higher injection rate of 50mA/min into the storage ring, which requires an injected beam with lowemittance, low energy spread and high beam orbit and energy stabilities. This goal is finally reached recently by upgrading the linac components and by dealing with rich and practical beam physics, which are described in this study.