Flexible and telescopic vacuum chambers for the APS bunch compressor

Abstract

The Advanced Photon Source (APS) bunch compressor was built with the goal of producing electron bunches with high peak current. Vacuum chamber liners were designed to, reduce the interaction of the electron beam with the surrounding chamber walls. The goal was to have the field of the beam encountering chamber walls that are smooth having diametrical changes that are well controlled. This paper shows the design and construction of our special bellows chambers that are used in the chicane and straight sections of the beamline. The bunch compressor in the APS linac has movable magnets so that the aspect ratio and the compressor displacements are variable. To accommodate this, two types of special chambers are needed: a flexible chamber for different bending angles and a telescopic chamber for length changes in the beamline.