Variable-period magnetostatic undulator designs based on iron-free current configurations

The design of a magnetostatic undulator based on iron-free current configuration is described. Equations describing its performance are derived. Based on this exercise, it is shown that other types of variable-period magnetostatic structures with significantly stronger fields could be implemented. A specific design for a variable-period dipole configuration with the potential for generating moderate fields on medium-energy (2-4 GeV) storage rings is proposed.>