CEBAF cryomodules: test results and status

The Continuous Electron Beam Accelerator Facility is under construction in Newport News, Virginia. When completed in 1994, the accelerator will be the largest installation of radio frequency superconductivity. Production of cryomodules, the fundamental cryogenic building blocks of the machine, has started. They consist of four pairs of 1497-MHz, five-cell cavities contained in separate helium vessels and mounted in a cryostat with appropriate end caps for helium supply and return. The first cryomodule has been successfully assembled, tested, and moved to the accelerator. Some of the individual components in this prototype performed below, but close to, the specification. As a whole, the cryomodule performs in a more than acceptable way for operation in the injector. It will provide 20 MeV to the electron beam with a tolerable dissipation of about 75 W at 2 K. A new cryomodule with full production components will replace this prototype.