ILC - ATF2 dc-magnet power supplies

In 2008 KEK is commissioning ATF2 - an extension to the existing ATF. ATF2 is a mockup of the final focus test beam accelerator envisioned in the ILC. SLAC is designing the power supply systems for the dc magnets in the ATF2, which will require 38 power supplies ranging from 1.5 kW to 6 kW, and currents from 50 A to 200 A, all rated at output voltages not higher than 30 V. Because of the extensive quantities of magnets required for the ILC, high availability is paramount to its successful operation, so the power supply topology chosen for the ATF2 uses N+l redundancy, with 50-A power modules to construct each power supply. These power modules are current-mode buck converters, which operate in parallel with each other and one redundant module. One bulk power supply provides off-the-line regulated dc input to a number of the power supply systems. Current stability requirements for the magnets range from 10 to 1000 ppm. A precision current transductor and a recently developed SLAC-built 20-bit Ethernet power supply controller will provide the current regulation required. In this paper we present the conceptual design, prototype results, and the status of the power supply systems for the ATF2.