Characteristics of the Synchrotron Radiation of Fourth-Generation Storage Rings

Fourth-generation storage rings (4GSR) based on multi-bend achromat (MBA) lattices promise to deliver stable X-ray beams with higher brightness and coherence than existing third-generation light sources. The basic ingredient in achieving higher brightness is a further reduction of the electron beam emittance in storage rings dedicated to light sources. These 4GSR lattices can lead to 1 to 2 orders of magnitude reductions in the beam emittance by employing a MBA, where many dipoles per cell are used to keep the dispersion function low inside the dipoles. Moreover, these low emittance beams are transported to the beam-line through the insertion device or center-bend, which is a permanent magnet with a 2 T magnetic field. In this paper, we will introduce the characteristics of the synchrotron radiation of 4GSR compared to present third-generation sources, PLS-II.