The Unilac Ion Source and Injection System

The design of the UNILAC injector was particularly governed by aspects of maintenance and reliable performance. Thus an open air 254 kV high gradient single gap acceleration was chosen for Uranium 11+ particles, corresponding to an injection energy of 11.7 keV/amu and a charge-to-mass ratio of 0.046. This allows fast ion source changes because only a short time for tube conditioning is required and takes into account the lifetime of present sources for multiply-charged heavy ions. Two independent Faraday-rooms, symmetrically arranged to the axis of the main accelerator, are housing each a 300 kV oil-insulated Cockcroft-Walton generator, a duoplasmatron and a Penning source with the associated equipment. Hereby a fast switch over to the stand-by source in case of an ion source failure is provided. Magnetic quadrupole lenses focus and match the beam through a magnetic deflection system, a 50 Hz chopper and a double drift buncher into the linac.