A 2.1-GeV ring design for SRC
A design for a twelve-sided 2.1-GeV electron storage ring is obtained. The design utilizes the combined-function magnet approach of the Max-IV design for 1.5-GeV and 3-GeV rings. The 2.1-GeV ring has an emittance of 1.5 nm-rad and circumference of 215 m, with twelve 5.5-m long straight sections. With a 100-MHz radiofrequency (RF) system, an adequate Touschek current-lifetime product of ~3000 mA-hours is computed. The lifetime is not limited by the computed dynamic aperture. Modeling of a passive fifth harmonic RF system suggests that a 100-MHz/500-MHz system may be successfully operated to increase the bunchlength and Touschek lifetime by a factor of four while suppressing typical parasitic coupled-bunch instabilities. For stable operation with ring currents up to 600 mA, microwave-instability simulations indicate that the reduced longitudinal broadband impedance should be less than 1.5 ohms. The properties of the ring design suggest that a low-emittance 2.1-GeV ring with a circumference of 215 m is a feasible upgrade path for the Synchrotron Radiation Center.