Integrated normal-conducting/superconducting high-power proton linac for the APT project

The baseline accelerator design for the APT (Accelerator Production of Tritium) Project is a normalconducting-superconducting proton linac that produces a CW beam power of 170 MW at 1700 MeV. Compared with the previous all-NC linac design, the NC/SC linac provides significant power savings and lower operating and capital costs. It allows a much larger aperture at high energies, and permits greater operational flexibility. The design has been approved by high-level technical panels and is published in a Conceptual Design Report. The high-energy portion is a superconducting (SC) RF linac employing elliptical-type niobium cavities, while the low-energy portion is a normal-conducting (NC) linac constructed from copper cavities. This provides an integrated accelerator design that makes optimum use of the two technologies in their appropriate regions of application. The NC linac, which consists of an injector, RFQ, CCDTL, and CCL, accelerates a 100-mA beam to 217 MeV. The SC linac is built in two sections optimized for different beam velocity spans, with each section made up of cryomodules containing 5-cell cavities and SC singlet quads in a FODO focusing lattice. Alternate SC linac designs are being studied that employ a doublet focusing lattice using conventional quadrupoles located between cryomodules.