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