The Challenges of Third-generation Synchrotron Light Sources*

Third-generation synchrotron light sources are specifically designed to operate with long insertion devices that produce very high brightness beams of synchrotron radiation. There are many such facilities now under construction, or in the design stage, allover the world. After a brief review of the main properties of the low emittance storage rings that form the heart of these facilities, we will discuss the particular challenges that accompany their design. These include: the effects of the strong sextupoles required for chromatic correction of the low emittance lattices; impact of machine imperfections on the dynamic aperture; the effects of the linear and nonlinear magnetic fields of the undulators; impedance consequences of long, narrow, undulator vacuum vessels; injection; and beam lifetime. As examples, we take the Advanced Light Source, currently under construction at the Lawrence Berkeley Laboratory, U.S.A., and the European Synchrotron Radiation Facility under construction in Grenoble, France.