The PSI 870 keV high intensity Cockcroft–Walton preinjector

As part of the program to increase the beam current from the Paul Scherrer Institute (formerly SIN) 590 MeV proton ring accelerator, a new injector system based on a 72 MeV isochronous cyclotron has been built. The preinjector for the 72 MeV machine consists of a 900 kV, 30 mA dc generator of the Cockcroft–Walton type, a high voltage dome housing a multicusp ion source with a 60 keV beam transport line, and a SF6 insulated acceleration tube. A general description and operational experience of the 870 keV preinjector and progress toward improving the H+ fractional output of the ion source will be given.