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Description
There are 96 combined function magnets (48 focusing and 48 defocusing) that have been in operation in the Fermi National Laboratory’s Booster without a critical failure requiring replacement for over 50 years. The Proton Improvement Plan-II (PIP-II) poses risk to these magnets and Fermilab does not currently have the tooling or knowledge of process to fabricate spares. A longer straight section is required by PIP-II to make room for new Orbital Bump magnets at the injection region. This will be accomplished by replacing one defocusing magnet on either side of the injection region with new shorter magnets (Booster Gradient Defocusing Short, or BGDS). Also, to reduce beam loss due to scraping at the extraction region, a defocusing magnet will be replaced with a similar magnet with greater vertical aperture (Booster Gradient Defocusing Wide, or BGDW) upstream of the septum magnet used for extraction. These gradient magnets are void-free monolithic structures accomplished by vacuum impregnating the core and all coils at the same time. They do not have a beam tube for the purpose of maximizing aperture while reducing physical dimensions, peak stored energy, and power consumption. Risk of failure, as well as need for spares, will increase dramatically with implementation of PIP-II due to the Booster frequency increasing from 15 Hz to 20 Hz and a consequent increase in peak to ground voltage. The BGDS and BGDW magnets will be fabricated in the same way as the current booster magnets so that future combined function magnet spares can be produced. BGDS and BGDW mechanical design and vacuum pressure impregnation technique will be discussed in this paper.
