Beam optics and dynamics in electron storage rings with ultralow emittance

Due to recent advances in the physics and technology of relativistic circular colliders, it is now possible to design storage rings whose emittance is close to the diffraction threshold of synchrotron radiation (e ~ 10 pm for the radiation critical wavelength of λ c ~ 1A). Methods for minimizing emittance by optimizing the magnetic structure without reducing the dynamic aperture and the energy acceptance, as well as possible implementations of these methods, are discussed in this paper.