Design and operation of the cryostat for the CESR-c superconducting wiggler magnets

As part of the "CESR-c" upgrade project, a full-scale prototype superferric wiggler module has been installed into the Cornell Electron Storage Ring (CESR) and successfully operated since October 2002. At least eleven more wigglers are to be installed to enable full operation of the CESR-c. The wiggler magnets are chosen to achieve the necessary damping for optimum operation of CESR-c at a beam energy of 1.88 GeV. The wiggler cryostat units are designed to be modular, of fixed length flange-to-flange, so that they can be easily installed and exchanged. The cryostat incorporates several novel features including a suspension system with very low heat leak that prevents any significant motion during cool down, a custom triple cryogenic feedthrough, and a helium vessel made in two halves, each enclosing a half-magnet. This article presents the design, fabrication, and operation of the CESR-c wiggler cryostat.