High-Currrent Regulated Supply, Combining Transistors and Magnetic Amplifiers, for the Oak Ridge Isochronous Cyclotron

Circuits are shown and design criteria given for a current-regulated power supply which is typical of 19 supplies of four types built for the Oak Ridge Isochronous Cyclotron. These supplies range from 6.25 to 34 kw with current ratings from 250 to 1200 amp. Current regulation and ripple of 1 part in 104 are obtained by separate ac and dc feedback circuits driving a bank of parallel power transistors in series with the load. The dissipation of the transistor bank is limited by a third feedback circuit, which drives a saturable reactor in the power supply to maintain a constant voltage across the transistor bank. The output can be varied from zero to maximum by setting a reference potentiometer which is supplied by a Zener reference with a low temperature coefficient. Plug-in circuits in the feedback networks allow versatility; any regulator can be used with a wide variety of magnets of varying time constants. A modular transistor bank simplifies construction and maintenance.