First operational tests of the positive-ion injector for ATLAS

The status of and the first operational experience with the he positive-ion injector for ATLAS are summarized. The new injector consists of an ECR (electron cyclotron resonance) ion source on a 350-kV platform followed by a superconducting injector linac of a new kind. In the first phase of this project, the ECR source, voltage platform, bunching system, beam-transport system, and a 3-MV injector linac were completed and tested in early 1989 by the successful acceleration of a 40Ar12+ beam. Most of the new system operated as planned, and the longitudinal emittance of the 36-MeV beam out of the injector was measured to be only 5π keV-ns, much smaller than the emittance for the present tandem injector. When completed in 1990, the final injector linac will be enlarged to 12 MV, enough to allow the original ATLAS linac to accelerate uranium ions up to 8 MeV/