Superconducting Helix loaded cavity for heavy ion acceleration

Half-wave helix loaded structures have been designed to increase the mass range of heavy ions which will be accelerated by the CEN Saclay superconducting accelerator. In this paper we shall list the main characteristics of these resonators; especially, the quality factor and the energy gain per charge measured with a 12C beam. The important advantages of these new structures are the broadness of the transit time factor curve which allows us to accelerate low velocity beams with a sufficient efficiency, and the simplicity of mechanical design which requires only two helix welds. We shall also give the performances achieved by the series of resonators which will be mounted into two of the six machine cryostats. The new superconducting accelerator will provide the first beams at the end of this year