Possible use of undulator radiation in VUV and soft x-ray radiometry

Abstract

A new generation of synchrotron radiation light sources covering the VUV, soft x-ray and hard x-ray spectral regions is under construction in several countries. They are designed specifically to use periodic magnetic undulators and low emittance electron or positron beams to produce high brightness near-diffraction-limited synchrotron radiation beams. Although they have been designed to maximize source brightness and flux, it may be possible to use specially designed undulators and wigglers in the new light sources for radiometry in the VUV and soft x-ray regions. Some of the novel features of the new sources are discussed, with emphasis on the Advanced Light Source, a third generation 1.5-GeV storage ring optimized for undulator use. A brief introduction to the physics of undulator radiation is presented. This is followed by a discussion of some of the challenges faced by users of these new sources, including high beam power, partial coherence, harmonics, optics contamination, and the unusual spectral and angular properties of undulator radiation. The limitations of the presently planned undulators as radiometric sources and the design criteria for a possible radiometry undulator are discussed.