Chinese Acad Sci, Inst High Energy Phys, Beijing 100039, Peoples R China
The conditions for ion trapping are studied in the case of uniformly distributed electron bunches and bunch trains in storage rings based on the linear theory. The formulas of the threshold current for ion trapping are derived by means of the Twiss parameters in the ion focused system. Based on the theory, the beam behavior observed in the dedicated synchrotron radiation operation of the Beijing Electron-Positron Collider (BEPC) is discussed. It is proposed to apply the bunch train in the BEPC storage ring in order to overcome the beam lifetime drop during the single electron beam operation.