Commissioning of the New High Intensity 72 MeV Injector II for the SIN Ring Cyclotron

Abstract

Commissioning of the SIN Injector II cyclotron started in spring 1984 and by spring 1985 a prpton beam current of 0.55 mA was extracted. The performance of the principal components of the overall injector can be summarized as follows: (1) The nominal ion source extraction voltage is 60 kV and the maximum current from the 860 keV Cockcroft-Walton pre-injector is presently about 10 mA DC; (2) a phase acceptance up to 40 deg can be achieved without a buncher, but making use of a third harmonic flattopping RF-system; (3) the 100 turns in the cyclotron are completely separated leading to an extraction efficiency of more than 99.9% Initial tests in combination with our 600 MeV ring cyclotron have resulted in a 0.18 mA beam on target. The majority of future operation of the 600 MeV cyclotron is scheduled to be with Injector II.- The next steps toward higher intensity are improvements of the ion source proton efficiency and the addition of a buncher in the injection line. The ultimate intensity limit is thought to be in the mA region due to an instability from longitudinal space charge forces.