Heavy Ion Storage Ring for Atomic Physics (HISTRAP) vacuum test stand for pressures of 10-12 Torr

HISTRAP (Heavy Ion Storage Ring for Atomic Physics) is a proposed synchrotron/cooler/storage ring accelerator optimized for advanced atomic physics research. The ring has a circumference of 46.8 m, a bore diameter of /similar to/15 cm, and requires a vacuum of 10-12 Torr to decelerate highly charged, very heavy ions down to low energies. To be able to test components and procedures to achieve this pressure, a test stand approximately modeling 1/16 of the ring vacuum chamber has been built. The 3.5-m-long test stand has been fabricated from 10-cm-diam components, with 316LN stainless-steel flanges. Prior to assembly, these components were vacuum fired at 950 0C at a pressure of 10-4 Torr. The test stand is bakable in situ at 300 0C. Pumping is achieved with two 750 l/s titanium sublimator pumps and one 60 l/s ion pump. Pressure is measured with two extractor ion gauges and a 10-4 partial pressure residual gas analyser. The roughing for the test stand consists of cryosorption pumps followed by a cryopump. A pressure of 4 x 10-12 Torr has been achieved