Design of the Medium‐Beta Cryomodule for the ISAC‐II Superconducting Heavy Ion Accelerator

ISAC‐II is an upgrade of the ISAC radioactive beam facility that includes the addition of 43 MV of heavy ion superconducting accelerator. The initial milestone in achieving this goal is the design and manufacture of a prototype medium‐beta cryomodule scheduled for completion late in 2003. A medium‐beta cryomodule comprises four superconducting cavities and one superconducting solenoid magnet. The cryomodule has an inventory of 190 liters of liquid helium at 4.5‐K under constant replenishment from the refrigeration system during normal operating conditions. This paper will describe the design and engineering of the medium‐beta cryomodule including the internal mechanical design and layout, LN₂ shielding, alignment method and expected thermal loads.