Variable-period undulators as synchrotron radiation sources

J. Synchrotron Rad. (2003). 10, 205–213

Basic concept for a variable-period undulator. The spaces with width α permit period variation along the z axis, and the blocks of high permeability material have a fixed width d. The periodic transverse undulator field is derived by the staggered arrays from the longitudinal field produced by a normal conducting or a superconducting solenoid.

Permanent-magnet undulators have served well in the production of bright X-ray beams. However, their fixed magnetic period limits their broad application, primarily their tunability. A novel concept for undulators with the capability to vary the length of the magnetic period for the production of synchrotron radiation is proposed based on staggered arrays of poles placed in a magnetic solenoid. The impact of such a 'variable-period undulator' on synchrotron science is very broad due its wide energy tunability and delivery of highly brilliant radiation without the burden of handling the high power load on first optics. This development would further contribute to future linac-based sources such as energy recovery linacs and free-electron lasers.