Magnetic Measurement Techniques for the Large-Scale Production of Undulator Segments for the European XFEL

The European X-ray free electron laser (EXFEL) facility is currently under construction [1 M. Altarelli, The European X-ray Free-electron Laser, Technical Design Report (2006). [Google Scholar]]. Using the principle of self-amplified spontaneous emission (SASE) [2 A.M. Kondratenko and E.L. Saldin, Part. Accel., 10, 207 (1980). [Google Scholar], 3 R. Bonifacio, C. Pellegrini, and L.M. Narducci, Opt. Commum. 50, 373 (1984).[Crossref], [Web of Science ®] , [Google Scholar]], intense FEL radiation is generated in three gap-tuneable undulator systems called SASE1, SASE2, and SASE3. The electron beam energy of the EXFEL is variable between 8.5 and 17.5 GeV. SASE1 and SASE2 are hard X-ray FELs using planar undulators with a period length of 40 mm, called U40s. By a suitable choice of the beam energy and undulator gap, the wavelength can be tuned from 0.05 to 0.4 nm. SASE3 is a soft X-ray FEL using planar undulators with a period length of 68 mm, called U68s. Under the same conditions, the wavelength can be tuned from 0.4 to 5.2 nm.