Design of the Aluminum Vacuum Chambers for the 3 GeV TPS Electron Storage Ring

The conceptual design of the vacuum systems for the electron storage ring of the Taiwan Photon Source (TPS) is described. The vacuum system for the synchrotron light source not only meets the specifications of an electron beam energy of 3 GeV and a beam current at 400 mA but also provides a safety factor of ~ 1.7 (or 3.3 GeV and 500 mA) at the upper bound. The vacuum system for the storage ring is built with consideration of the following factors: (1) Sustaining the ultrahigh vacuum (UHV), (2) Highly stable vacuum system with vibration level < 0.5 mum, (3) Vacuum chambers with low impedance, (4) Thermal absorbers, and (5) Highly reliable vacuum system with least trip rate, etc. to ensure the stability of the circulating low emittance electron beam. The aluminum alloys are selected for the vacuum chambers to meet the design requirements. The concept of the design will be described.