Commissioning of the Diamond Light Source storage ring vacuum system
Cox, Matthew; Boussier, Bastien; Bryan, Stephen; Macdonald, Brian; Shiers, Hugo United Kingdom
Diamond Light Source is a new 3 GeV synchrotron light source recently commissioned in the UK. First user beam was delivered in January 2007.
The main vacuum systems are a 561.6 m circumference 3 GeV electron storage ring and a 158.4 m circumference 0.1 - 3 GeV booster ring.
The storage ring is designed to operate in the 10-9 mbar pressure region with 300 mA of stored beam after a period of beam conditioning. Pumping is provided by 500 discrete noble diode ion pumps, supplemented by titanium sublimation pumps and NEG cartridge pumps in critical areas. Vacuum vessel construction is mainly from 316LN stainless steel. Only 25% of the storage ring circumference could be baked out in-situ; an ex-situ bakeout process was used for the remainder of the storage ring vessels followed by installation under vacuum.
All Diamond vacuum systems are operating reliably and according to expectations. Without stored beam the storage ring static pressure is 4 - 5 x 10-10 mbar and the residual gas is more than 90% hydrogen. With stored beam, the storage ring dynamic pressure follows a D-0.8 law where D is the beam dose (integrated current x time ) in line with observations from other storage rings. The stored beam lifetime also increases as expected with beam dose.
This paper presents recent performance data and operating experience from the Diamond vacuum systems