Centering of the test ion trajectories in the central region of the VINCY cyclotron

To minimize beam losses and increase efficiency of the machine the central region of a cyclotron must provide a number of beam guiding conditions. The first requirement that has to be fulfilled is that guiding center of the beam has to coincide with the cyclotron center. For a multipurpose machine, such as VINCY Cyclotron, this condition has to be satisfied for all operating range ion beams if not exactly than as close as possible. The central region, as well as other beam transport regions in a cyclotron, is designed using computer program for ion beam dynamics simulation. As an input for the beam transport simulation code, approximate electric field of the four acceleration gaps has been developed and used to study decentering of the VINCY Cyclotron test ions. The results are used to suggest the geometry of the central region that provides the best centering for all test ions. (author)