Design and first commissioning of a new mode with lower emittance in the SSRF storage ring

A new mode is designed with an emittance of 2.47 nm.rad at 3.0 GeV beam energy, lower than the nominal mode of the Shanghai Synchrotron Radiation Facility (SSRF) storage ring. Details of the linear optics design and the nonlinear optimization are presented ill this paper. During Phase I commissioning of the storage ring we tested the new optics mode and some expected results were obtained. After restoring the linear optics by means of the linear optics with closed orbit, technique; the main parameters of the real machine agree well with the designed values and the injection efficiency and beats lifetime are acceptable.