  The accelerator for the APT Project is a 100 mA CW proton linac with an
output energy of 1030 MeV. A High Energy Beam Transport (HEBT) conveys the beam
to a raster expander, that provides a large rectangular distribution at a
target/blanket (T/B) assembly. Spallation neutrons generated by the proton beam
in the T/B reacts with Helium-3 to produce tritium. The design of the APT linac
is an integrated normal-conducting (NC)/superconducting (SC) proton linac; the
machine architecture has been discussed elsewhere [1]. The NC linac consists of
a 75 keV injector, a 6.7-MeV 350-MHz RFQ (radio frequency quadrupole), a 96-MeV
700-MHz CCDTL (coupled-cavity drift-tube linac), and a 700-MHz CCL
(coupled-cavity linac), with an output energy of 211 MeV. This is followed by a
SC linac, that employs 700-MHz elliptical niobium 5-cell cavities to accelerate
the beam to the final energy. The SC linac has two sections, optimized for beam
velocities of b =0.64 and b =0.82. Each section is made up of cryomodules
containing two, three, or four 5-cell cavities, driven by 1-MW 700-MHz
klystrons. The singlet FODO lattice in the NC linac transitions to a doublet
focusing lattice in the SC linac, with conventional quadrupole magnets in the
warm inter-module spaces. This doublet lattice is continued in the HEBT. An
overview of the current linac design will be presented.
