CERN Accelerating science

  Powering strategy of SESAME magnets
  by Livia Lapadatescu, Agnes Szeberenyi with Miguel Cerqueira Bastos (CERN)

The power converter team with the first of 10 pallets that arrived at CERN with all the quadrupole power supplies (focusing and defocusing) and with the focusing sextupole power supplies. Credits: CERN and SESAME

The magnet system with its power supplies are a major component of the SESAME light source main storage ring. The main objective of the power supplies activity under the collaboration between CERN, European Commission and SESAME is to define the powering strategy and deliver the power converters and corresponding control elements to SESAME. This includes specifications, procurement and testing of all power and control components.

In the last three months, the Magnet Power Supplies activity of the CESSAMag project has seen some major milestones achieved. After reviewing the typical powering requirements of modern light sources and understanding the main differences with respect to high-energy particle accelerators, the CERN and SESAME team devised a powering strategy focused on providing flexibility and performance whilst minimizing machine downtime and facilitating maintenance procedures. This strategy was approved by both CERN and SESAME Technical Committees. It relies on the use of an existing, “proven in use”, control system to run commercial power supplies, which in the case of the quadrupoles are off-the-shelf products. With this strategy SESAME has full control over the performance of the current loop and benefits from the standardization of the control electronics. The use of commercial power supplies, easily and quickly replaceable, also improves maintenance and spare management.

The interface and DAC board, developed by the power converter team. Credits: CERN and SESAME

The control solution described above led to  the decision of using the latest power supply controller from the Paul Scherrer Institute (PSI). The CESSAMag team is the first to integrate the new generation of the PSI controller in the powering system of another light source.

The powering of the magnets in the SESAME main storage ring will be done in series for the dipole and sextupole magnets and individually for the other magnet types. The individual powering of quadrupoles was not originally foreseen and it was adopted to achieve increased flexibility, following discussions with experts from other light sources. The 8 magnet types (dipole, focusing quadrupole, defocusing quadrupole, focusing sextupole, defocusing sextupole, V-correctors, H-correctors, skew quads) require 6 different types of power supplies.

All the power supplies for the quadrupole and corrector magnets as well as the PSI electronics for the control system and the gateways have been delivered to CERN. Testing of all these elements will now start at CERN and they will be delivered and integrated into the SESAME system mid-2015.