Digital current regulation for dipole magnets in proton accelerators

In proton synchrotrons a high field quality for bending fields is needed. Therefore, the control system for the dipole magnet current has to be of good performance. One way to tackle the problem is a digital control system. A digital control system is resistant to ageing and variations of temperature and voltage. An integration to a more complex digital control system is easy made. The tolerances for field and current of the proton synchrotron DESY III are derived. A short introduction to controller theory is given and some specialities of digital controllers are described. A digital controller for dipole current control, whose main component is not a standard controller with proportional, integral and derivative part, is designed, built and tested with a software and a hardware model. The results are compared with the presently used analog controller for the dipole current of DESY III and show that the digital controller should be a good alternative. (orig.)