The New 20 kA 80 V Power Supply for the 520 MeV H$^-$ Cyclotron at TRIUMF

The new 20 kA, 80 V power supply for the main magnet of the 520 MeV H⁻ Cyclotron at TRIUMF was awarded to OCEM. It has replaced the original system (commissioned in 1976) based on a series pass regulator. The final acceptance tests have demonstrated the com-pliance with the project specifications, especially for the high current stability required for the Cyclotron operation. The current stability is ±5 ppm, including current ripple, for a period of more than 8 hours of continuous operation. In addition, the magnetic field can be further stabilized us-ing feedback of a flux loop signal. OCEM designed the power supply to use the third gen-eration of Function Generator/Controller (FGC3) control electronics from CERN. This was chosen to obtain the high current stability required by TRIUMF. This collaboration was facilitated through a Knowledge Transfer agreement between CERN and OCEM. The power supply commis-sioning has been performed as a collaboration between OCEM, TRIUMF and CERN. This paper describes the topology of the power supply, the control electronics, the high-precision current measure-ment system and the associated software as well as the commissioning results carried out with the magnet.