Operational experience with the 450 kV injector for the superconducting cyclotron

In order to get a correct bunching of the tandem beams to be injected into the K-800 superconducting cyclotron at LNS and to improve further the transmission inside the tandem, the construction of a new injector providing 450 keV negative ions became necessary. The project, funded in 1990, is now complete. The commissioning of the 450 kV injector has been carried out paying particular attention to some technical problems: 1) the presence of two different sources, which permits to switch easily from one source to the other, has required to double all the hardware, except for the analyzing magnet and for the gas box, in order to be effective in reducing downtimes for maintenance: 2) the reduction of the electrical noise, which disturbs the computer control system; 3) the management of 79 analogic parameters and 110 digital parameters, which has been performed in an environment where the classical control system via insulated bars fails because of the high potential gradient (10 kV/in), one of the highest ever obtained in conditioned air environment for injectors. The main features of the 450 kV injector will be summarized. The main details of the commissioning with the platform performances will be presented and some details of ion optics will be given.