On the Magnetic Designing of Compact Alpha-Magnets

Alpha-magnets present unique achromatic properties for beam instrumentation and phasespace manipulation. Nowadays they are acquiring a substantial interest for application in a rapidly growing number of facilities around the world: Free Electron Lasers, far infrared and THz sources, inverse Compton sources of ultra-bright hard X-rays. However, classic design of an alpha-magnet based on hyperbolic poles makes it dimensions large, resulting in significant weight and cost. Several magnetic designs of alpha magnets with reduced dimensions especially for low energy electron beams is considered here including very compact alpha magnets based on permanent magnets with about flat poles as well as compact electromagnetic designs with co-axis coils and substantially non-hyperbolic or truncated poles. These novel design approaches can be applied in relatively small facilities where weight and/or space are limited.