Design of a polarised light beamline in the energy range of 30-4000 eV

Abstract

This article describes the design of a possible polarised light beamline for magnetic circular dichroism and photoemission experiments on a bending magnet source of 2.5 GeV storage ring, Indus-2. It will have an energy range of 30-4000 eV and will deliver circular as well as linearly polarised light to perform absorption and photoemission experiments covering relevant L and M edges of most of the elements. The beamline optics consists of a vertically moveable aperture for polarisation selection. It has three spherical gratings and a double crystal monochromator necessary for energy selection in low and high-energy ranges respectively. Corresponding pre- and post-mirror optics, which is common for both the monochromators is the highlight of this design. Detailed ray-tracing calculations, which were carried out to evaluate and optimise the performance of the proposed beamline, are presented in this article.