Development of a short-period hybrid wiggler

A short-period wiggler (λw = 12 mm, g = 6 mm, Nw = 40) was designed and wiggler parameters were optimized by 2-dimensional field analysis to enhance the magnetic field. According to this design, a trial wiggler (λw = 12 mm, g = 6 mm, Nw = 10) was manufactured and its magnetic field was measured. It has a hybrid type structure, with NdFeB permanent magnets and low carbon steel polepieces. The measured field strength was 0.44 T (K = 0.5). We also demonstrated the usefulness of the variable field adjustment method by making a by-pass circuit with a backside shim structure. The maximum adjustment value was 4%.