A CONCEPT OF A UNIVERSAL SUPERCONDUCTING UNDULATOR

Tiny round electron beams of free-electron lasers and relatively new diffraction-limited storage rings make possible the utilization of electromagnetic helical undulators based on double-helical windings. It has long been understood that a coaxial pair of double-helical windings can generate helical as well as planar magnetic fields [1]. Such a coil structure can potentially be realized with superconducting windings, thus forming the concept of a universal superconducting undulator (Universal SCU). An example of a possible universal SCU for the recently suggested Advanced Photon Source (APS) multibend achromat storage ring is given in this paper. The results of the magnetic simulation together with initial design considerations are presented.