Characteristics of Inversion Operation on Fermilab Phase Controlled Pulsed Power Supplies

A well known property of phase controlled rectifiers with pulsed inductive loads is the ability to advance firing angles from full rectification (positive voltage) to full inversion (negative voltage). Though these properties have been effectively used in the Main Ring power supplies, they have not been extensively utilized for beam line magnet power supplies. Modifications to permit advancing phase angle sufficiently to permit inversion were made on TransRex 500 KW power supplies and Ling 55 KW power supplies. The objective of these modifications was to rapidly reduce the current in magnet loads to zero upon command. The modifications required and the performance of the power supplies are discussed.