High-field strong-focusing undulator designs for X-ray Linac Coherent Light Source (LCLS) applications

Enabling instrumentation and technology for 21st century light sources

“…vertically polarizing planar devices, some designs for variable polarization, e.g. Delta [34] and Apple-Ill [35] designs, and some superconducting designs, e.g., helical windings on a round beam tube [36,37], (b) ultra-small-gap, (< 4 mm) devices [38], and (c) specialty designs for small emittance, e.g. crossed undulators capable of fast polarization switching [39].…”

“…Furthermore, conceptual and prototype designs have already been developed for (a) superconducting elliptically polarizing undulators (SC-EPUs) [50], (b) stacked HTS undulators [40], (c) micro-undulators [40], and (d) helical SCUs [36,37], all aimed to meet specific needs for ultimate performance capability at future light source applications.…”

Design features of a planar hybrid/permanent magnet strong-focusing undulator for free electron laser (FEL) and synchrotron radiation (SR) applications

“…The proposed structure is seen to be of the "separated-function" type, allowing the quadrupole focusing to be implemented basically independently of the dipole field structure [11]. There are a number of possible implementations; for some of these the axially-magnetized PM material immediately above the axis can: 1) be excluded.…”

“…For Q ≥45 T/m, alternative techniques need to be employed [7][8][9][10]. In this paper, the planar-PM multipole technology proposed in recent years [7,8] is explored as a basis for a strong-focusing LCLS undulator field design [4,11]. The r&d associated with this work anticipates the eventual development of photocathode (pc) rf guns and linac-based compressor/transport systems that will deliver emittances of 1 mm-mr or less to the LCLS insertion device.…”