Advances in Undulator Technology at STI Optronics

Twenty-one undulators and wigglers have been designed and built by STI Optronics since 1980 for free-electron laser (FEL) an synchrotron radiation application. Work at STI in the technology of undulators and wigglers has progressed significantly from its first pure rare-earth permanent magnet (REPM) device based on the Halbach geometry. The technology at STI changed emphasis with the development of its first 5-mete hybrid REPM undulator (THUNDER). This undulator has several characteristics that are still important considerations for self-amplifies spontaneous emmission FELs. These included optically phased sections, a distributed vacuum system, and integrated beam diagnostics and correction.

STI has made several additional advances in hybrid undulator technology with the development and patenting of both shim tuning and the wedged-pole geometry. These were both incorporated into a 10-m-long -modular magnetic structure, with integrated diagnostics and beam control, and a control system capable of complex self-designing field tapers, in the NISUS (Near-Infrared Scaleable Undulator System).

In this paper we will review the recent enhancements that STI has developed in the field undulator technology. These will be highlighted and examined in the context of the STI designed and built Advanced Photon Source (APS) Undulator A systems (APS-UA). These particular devices form the principal synchrotron radiation light sources for the APS and have been optimized in several aspects required to enhance FEL performance.