Review of Current FFAG Lattice Studies in North America

There has been a revival of interest in the use of fixed field alternating gradient accelerators (FFAGs) for many applications, including muon accelerators, high-intensity proton sources, and medical applications. The original FFAGs, and those recently built in Japan, have been based on a so-called scaling FFAG design, for which tunes are constant and the behavior in phase space is independent of energy with the exception of a scaling factor. Activity in the US and Canada has instead mostly focused on nonscaling designs, which, while having the large energy acceptance that characterizes an FFAG, do not obey the scaling relations of the scaling FFAG. Most of these designs have been based on magnets with a linear midplane field profile. A great deal of analysis, both theoretically and numerically, has occurred on these designs, and they are very well understood at this point. Some more recent work has occurred on designs with a nonlinear field profile. Since no non-scaling FFAG has ever been built, there is interest in building a small model which would accelerate electrons and demonstrate our understanding of non-scaling FFAG design