SPEAR III-a brighter source at SSRL

By replacing the magnets and vacuum chamber for the 3 GeV SPEAR II storage ring, the natural emittance of the machine can be reduced from 130 to 18 nm-rad and the stored current can be raised from 100 to 200 mA with a 50 h lifetime. This configuration increases focused photon flux for insertion device beamlines by an order of magnitude and the photon brightness for future undulators would exceed 10/sup 18/ at 5 keV. Due to a higher critical energy, the photon flux in the 20 keV range for bending magnet beamlines increases by more than two orders of magnitude. We present preliminary SPEAR III design study results and plans to implement the facility upgrade with minimal downtime for SSRL users.