Advances in FEL undulator technology at STI Optronics

Undulators (wigglers) form an essential basis for free-electron laser and synchrotron radiation systems. Undulator concepts for producing higher magnetic field strength with improved field quality are reviewed. Shim-tuning methods have permitted tighter magnetic field tolerances than previously achieved. These include pole-to-pole field uniformity, trajectory straightness, and higher order moments. A key figure of merit is the optical phase error, which determines the coherence of the light generated in the device. Coherence is a strict requirement for maximizing gain in FELs and maintaining spectral intensity in synchrontron radiation sources with low emittance.