ACTIVITIES ON HEAVY ION RFQ AND RF SUPERCONDUCTING CAVITIES AT PEKING UNIVERSITY*

Progress on an Integrated Split Ring (ISR) RFQ with water-cooled mini vane electrodes was reported. N+, O+ and O- ions have been accelerated to more than 300 KeV. The beam transmission efficiency of the RFQ reached more than 84 % with an average current of ~38.4 µA. Feasibility study of accelerating both O+ and O- ion beams simultaneously in the same RFQ was also performed. An ISR RFQ for accelerating oxygen ion beam up to 1 MeV was designed and constructed. Two superconducting cavities with China made niobium were successfully manufactured and tested by the RF Superconductivity group. A DC photo cathode electron gun with a 2MeV superconducting booster and a Cu-Nb sputtering system have been designed, manufactured and installed. The feasibility of a heavy ion superconducting booster with sputtering Nb QWR cavities was studied in collaboration with CIAE for their proposed project of Beijing Radioactive Nuclear Beam Facility. Both SC and RFQ groups of PKU are collaborating with IHEP and CIAE for a new proposal of accelerator driven nuclear energy source. 1 HEAVY ION RFQ The RFQ group of Peking University has engaged in developing ISR RFQ cavities for ion implantation. A 300 KeV cavity was developed and studied extensively with a series of beam tests. A 1 MeV cavity was designed and constructed. The main parameters of these two cavities are shown in Table 1