Quantitative evaluation of magnet hysteresis effects at LANSCE with respect to magnet power supply specifications

The proton beam in the LANSCE accelerator is guided and focused almost exclusively by electromagnets. Magnet hysteresis has had significant impacts on the tuning of the LANSCE accelerator. Magnet hysteresis can also have an impact on magnet power supply (MPS) control, regulation and repeatability requirements. To date, MPS performance requirements have been driven by the requirements on the magnetic fields as determined by the accelerator physicists. Taking hysteresis effects into account can significantly change MPS requirements, as some requirements become more stringent and some are found to be over specified. Overspecification of MPS requirements can result in significant increases in MPS cost. Conversely, the use of appropriate MPS requirements can result in significant cost savings. The LANSCE accelerator´s more than three decades of operation provide a wide variety of MPS technologies and operational experience. We will survey the LANSCE MPS history and determine how performance specifications can be refined to both reduce costs and improve the operators abilities to control the magnetic fields.