Challenges for magnetic design of a compact booster fed by single power supply

In design of full energy Booster injectors, commonly used in the modern accelerator facilities, there is a tendency of avoiding saturation of the magnetic elements in order to avoid losses associated with tune change during the energy ramp. Typical maximum field in the bending magnets of the modern Booster projects of 1.0-1.4 T results in the large circumference. For 0.27-1.2 GeV full energy Booster injector for the Duke FEL storage ring, recently under design and fabrication, there was an ultimate goal to fit it into existing storage ring room to avoid cost extensive building construction. Therefore, the Booster ring has to be compact, therefore the maximum field in the bending magnets was accepted 1.76 T. With a different level of saturation in the bending magnets, focusing and defocusing quadruples it was not possible to avoid a tune change with the energy rise. However, the ratio of saturation levels for the elements was optimized to avoid crossing of any significant resonance while ramping through the entire energy range. The lattice was simulated for different energies based on the results of 3D calculations of the magnetic elements with the use of MERMAID 3D code. Another challenging part of the design was supplying all the dipoles and quadrupoles by single power supply.