ANL, Argonne, Illinois, USA
Tubular vacuum chamber assemblies made of aluminum, copper and stainless steel alloys will be used in the new Multi Bend Achromat (MBA) storage ring that is being developed at Advanced Photon Source (APS). Details of the new lattice magnet system design and ring impedance considerations continue to drive these vacuum chambers to smaller dimensions and thinner walls with tighter geometric tolerances under higher thermal loads. It is important to carefully evaluate the methods used to join these dissimilar metal components looking for compromise in primary strength, permeability, electrical and thermal properties while still creating structures that are ultra-high vacuum compatible and leak-tight. This paper visually details the underlying metallurgical changes that occur when joining various combinations of aluminum, OFE copper, GlidCop® and stainless steel using brazing, bonding and welding techniques. Each of the techniques has its advantages and disadvantages with engineering and economic consequences.
