Piggy-Back Power Supplies for Magnet Systems

In accelerator facilities, particularly beam switchyards, it is common to have two or more related magnets which require nearly the same dc current. Presently the magnets are energized from separate sources, or from a single current-regulated source, with the magnets connected in series, and current-sink shunts across one or more of the magnets to obtain the difference. This article describes the advantages of economy, efficiency, reliability, and flexibility which accrue if auxiliary power supplies are used to trim the currents by the addition of more current to one or more magnets.