Development of synchrotron control for Heavy-Ion Medical Accelerators

The power supplies for the main bending and quadrupole magnets of the Heavy-Ion Medical Accelerator (HIMAC) in Chiba are controlled by preset current and voltage patterns, which are created by a pattern-creation program. It has been observed that a deviation between the preset current and the actual one becomes very large when newly created patterns are applied to the power supplies. This deviation is attributed to the incorrect parameters used for calculations of the voltage pattern in the pattern-creation program. In order to reduce the deviation, we have analyzed the values of resistance and inductance using the actual data of the current and voltage patterns. As a result, more than 10% difference was found between the conventional and newly calculated parameters. By applying the new parameters to the pattern-creation program a reduction of the deviation was confirmed.