Rubin, D. L. Crittenden, J.A. Shanks, J.P. Wang, S. JACoW Geneva, Switzerland 978-3-95450-180-9 10.18429/JACoW-NAPAC2016-WEPOB36 English 980-983 WEPOB36 ion undulator lattice injection emittance Contribution to a conference proceedings 2017 2017-01 http://dx.doi.org/10.18429/JACoW-NAPAC2016-WEPOB36 https://jacow.org/napac2016/papers/wepob36.pdf The planned upgrade of the Cornell Electron Storage Ring as an X-ray source for CHESS will include an increase in beam energy and decrease in emittance from 100 nm-rad at 5.3 GeV to 30 nm-rad at 6 GeV, increase in beam current from 120 to 200 mA, continuous top-off injection of the single circulating beam, and four new zero dispersion inser- tion straights that can each accommodate a pair of canted undulators. The existing sextant of the storage ring arc that serves as the source for all of the CHESS X-ray beam lines will be reconfigured with 6 double-bend achromats, each consisting of two pairs of horizontally focusing quadrupoles, and a single pair of combined-function gradient bend magnets. The chromaticity will be compensated by the existing sextupoles in the legacy FODO arcs. We describe details of the linear optics, sextupole distributions to maximize dynamic aperture and injection efficiency, and characterization of magnetic field and alignment error tolerance.