High Precision Magnet Powering for the SESAME Storage Ring

SESAME is the first synchrotron light source for the Middle East and is expected to start its operation mid-2017. It is composed of a 22 MeV Microtron, a 0.8 GeV booster synchrotron and a 2.5 GeV storage ring. The storage ring magnets and power supplies were designed, produced and validated under the framework of a collaboration between SESAME and CERN, supported by the European Commission. The power supply control strategy for the SESAME main ring follows the same model used in the LHC, where the power supplies are voltage sources bought from industry, to which a specially designed control unit and current sensors are added to implement a high precision current source. This strategy provides modularity, ease of maintenance, better control over performance and flexibility for the machine. Machine flexibility is further enhanced by individually powering the quadrupole magnets. In this paper, the powering strategy, design and validation of the magnet power supplies are described. Some of the challenges faced during those phases are discussed. Finally, performance results are presented, showing stability of the dipole power supply at nominal current of about 10 parts per million.