Transverse gradient in Apple‐type undulators. (7th April 2017)

• Record Type: Journal Article
• Authors: Calvi, M.; Camenzuli, C.; Prat, E.; Schmidt, Th.
• Is Part Of: Journal of synchrotron radiation. Volume 24:Part 3(2017)
• Page Start: 600
• Page End: 608
• Publication Date: 2017-04-07
• Subjects: soft X‐ray line -- Apple‐type undulator -- transverse gradient undulator; Synchrotron radiation -- Periodicals; Free electron lasers -- Periodicals; 539.73505
• DOI: 10.1107/S1600577517004726
• Languages: English
• ISSNs: 0909-0495

Abstract

Abstract : This theory demonstrates the existence of a variable transverse K gradient in Apple‐type undulators. It is supported by numerical simulations to assess the limits of this analytical approach. Abstract : Apple‐type undulators are globally recognized as the most flexible devices for the production of variable polarized light in the soft X‐ray regime, both at synchrotron and free‐electron laser facilities. Recently, the implementation of transverse gradient undulators has been proposed to enhance the performance of new generation light sources. In this paper it is demonstrated that Apple undulators do not only generate linear and elliptical polarized light but also variable transverse gradient under certain conditions. A general theoretical framework is introduced to evaluate the K ‐value and its transverse gradient for an Apple undulator, and formulas for all regular operational modes and different Apple types (including the most recent Delta type and Apple X) are calculated and critically discussed.