Vacuum system for the LBL Advanced Light Source (ALS)

A 1.5 to 1.9 GeV synchrotron light source is being built at LBL (Lawrence Berkeley Laboratory). The vacuum system is designed to permit most synchrotron photons to escape the electron channel and be absorbed in an antechamber. The gas generated by the photons hitting the absorbers in the antechambers will be pumped by titanium sublimation pumps located directly under the absorbers. The electron channel and the antechamber are connected by a 10 mm high slot that offers good electrodynamic isolation of the two chambers for frequencies affecting the stored electron orbit. Twelve 10 m long vessels constitute the vacuum chambers for all the lattice magnets. Each chamber will be machined from two thick plates of 5083-H321 aluminum and welded at the perimeter. Machining both the inside and the outside of the vacuum chamber permits the use of complex and accurate surfaces. The use of thick plates allow flanges to be machined directly into the wall of each chamber, thus avoiding much welding