Operation experiences with the test section of a superconducting heavy ion post accelerator

The 0.5 MV test section of a superconducting heavy ion post accelerator built at Karlsruhe was operated for 1000 h at the beam line of the MP tandem at Heidelberg. Prototype tests carried out under realistic conditions now ensure the basis for the detailed design of a full scale accelerator. The performance tests reported here include 500 h of high field operation and 40 h of beam acceleration time. Poor vacuum conditions were found to increase electron emission in the superconducting resonators. The surface properties however could be restored by a single oxipolishing step. Beam loss during long term operation was simulated by direct ion irradiation at the operating temperature and at 300 K. A total dose of up to 2 x 1014 Ni-ions per cm2 (average value over 12 cm2) was found to have no influence on the superconducting surface properties. The cooling system and the rf control system were found to operate satisfactory. The required field stability was reliably obtained