Increasing the Energy of the Fermilab Booster

The Fermilab booster accelerator was originally conceived for acceleration of protons with an injection energy of 200 MeV to an extraction energy of ten GeV (to the 500 GeV main accelerator). Early booster operation has been limited to eight GeV. The booster beam will be more acceptable to the main accelerator if extraction is at ten GeV, thus we are now modifying the booster magnet system for ten GeV acceleration. Regulation of the booster magnetic field for injection at 200 MeV was a task even when operating to eight GeV. This paper outlines the approach which was adopted and how it relates to the ten GeV attempt. Further, it highlights the problems encountered in the design of any AC magnet system.