This paper describes the vacuum system for the National Synchrotron Light Source (NSLS) which is now under construction at Brookhaven National Laboratory (BNL). The system will consist of an electron linac, booster, vuv and x-ray storage rings, and up to 44 experimental beam lines. The pressures will range from 10** minus **7 Torr in the linac and booster, to 10** minus **1**0 Torr (without beam) in the storage rings. Stringent quality control and cleaning procedures are necessary to reduce the adverse effects of hydrocarbon contamination on optical elements which are used for beam handling. This thought is also reflected in the selection of materials, pumps, and other vacuum components, as well as in fabrication techniques. Sputter ion pumps are used throughout with distributed ion pumps and titanium sublimination pumps on the storage rings. Rough pumping is done with liquid-nitrogen-trapped turbomolecular pumps. In situ argon glow discharge conditioning is planned for the storage rings to reduce the desorption due to synchrotron radiation.
