Field certification of a high strength tapered hybrid undulator

Abstract Short wavelength, high efficiency free electron laser (FEL) operation imposes stringent specifications on undulator performance in order to maintain interaction strength. As part of the Boeing Aerospace Company, Spectra Technology Visible Oscillator Experiment, the Tapered Hybrid Undulator (THUNDER) meets the requirements imposed by high-efficiency visible rf-linac operation. The magnetic measurements used to validate the performance of THUNDER are presented. The specific design criteria and the tolerances they establish are discussed as well as the magnetic measurements that validate them. The electron beam diagnostic stations and their performance is also presented. The performance of THUNDER serves as a bench mark for undulator/wiggler designs central to long-wiggler FELs and advanced synchrotron radiation sources.