Lattice options for a 5 GeV light source at Cornell

Cornell University has proposed an Energy Recovery Linac (ERL) based synchrotron-light facility which can provide improved X-ray radiation due to the high beam quality which is available from a linac. To additionally utilize beam currents that are competitive with ring-based light sources, the linac has to operate with the novel technique of energy recovery. Cornell plans to address the outstanding issues of high-current injector, higher-order mode damping and extraction from superconducting RF environment, etc. in a downscaled prototype ERL prior to submitting a proposal for a full-scale machine. The flexibility of linacs allows for different modes of operating the ERL X- ray source, each of which requires specific manipulations of longitudinal phase-space that restrict the choice of the lattice. Here we discuss the different proposed modes of operating the ERL X-ray source and present options for corresponding lattices.