ANL, Argonne
Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
The ongoing energy upgrade of the heavy-ion linac ATLAS at ANL includes a new cryomodule containing seven 109MHz β=0.15 quarter-wave superconducting cavities to provide an additional 15 MV voltage. Several new features have been incorporated into both the cavity and cryomodule design. For example, the cryomodule separates the cavity vacuum space from the insulating vacuum, a first for TEM cavities. The cavities are designed in order to cancel the beam steering effect due to the RF field. Clean techniques have been applied to achieve low-particulate rf surfaces and are essential for reliable long-term high-gradient operation. The sealed clean subassembly consisting of cavities, beam spools, beam valves, couplers, vacuum manifold, and support frame has been attached to the top plate of the cryomodule outside the clean room. Initial commissioning results are presented. The module was designed and built as a prototype for the Facility for Rare Isotope Beams (FRIB) driver linac, however, a similar design can be effectively used in the front-end of SC proton linacs based on TEM-class SC cavities.
