Design of a 2.1-GeV electron storage ring

A 2.1 GeV electron storage ring can serve as a third- generation light source for photon energies of 1 -2000 eV. We design a ring with emittance of 1.5 nm-rad, circumference of 215 m, and twelve 5.5-m long straight sections. With a 100-MHz radiofrequency (rf) system, the computed Touschek current-lifetime product is 2800 mA- hr. Two passive fifth-harmonic cavities may be used to suppress longitudinal parasitic coupled-bunch instabilities while increasing the bunch length and lifetime by a factor of four. For stable operation with ring currents up to 600 mA, microwave-instability simulations indicate that the reduced longitudinal impedance should not exceed 1.5 ohms.