Short Period Model Helical Undulator for the ILC - Design and Demonstration

The goal of this research is the design and construction of short-period helical undulators for the International Linear Collider (ILC) thereby addressing a specified accelerator-technology requirement. The positron supply for the ILC will be generated by shining a 285 kW beam of 10 MeV photons onto a metallic target. The photons themselves are to be generated from a series of 100 2-m-long short-period double-helical undulator units energized by a 150 GeV electron beam. We will develop a special Nb3Sn insulated strand for the winding of the undulator. A three-stage R & amp;D program is planned in which: (1) superconducting strand is developed and manufactured, (2) Based on the FEM modeled design from Phase I, a 12 mm period undulator will be wound on armatures with optimized designs and tested, (3) FEM modeling will be used to optimize the geometry design of the armature, recommendations will be made for the design and construction of undulators with shorter periods. , (4) The designs and construction of undulators with shorter periods, 12 mm, 11.5mm, 11 m and 10 mm, will be wound and tested. An innovative tube-type Nb3Sn conductor intended for stable operation at 4 K in the field range below 4 T has been developed and insulated, and 14 mm period undulator was made and tested successfully. The overall Phase-I successful experience will provide a basis for the full FEM modeling, designing, and testing of shorter period helical undulator to be wound from fine-filament, stable, Nb3Sn strand. Commercial Applications and Other Benefits: The strand manufacturing and coil design/winding experience developed under this program will have wide ranging benefits. Tube-type Nb3Sn strand, characterized by its flux-jump stability at low fields and low persistent-current magnetization will find many accelerator applications. It will benefit the winding of: (i) light-source wiggler and undulator magnets in general, (ii) hadron-collider dipoles. Furthermore, undulators developed under the program will facilitate the upgrading of synchrotron light sources worldwide.