FRIB, East Lansing, Michigan, USA
The Facility for Rare Isotope Beams (FRIB) will utilize a powerful, superconducting heavy-ion driver linac to provide stable ion beams from protons to uranium, at energies of > 200 MeV/u at a beam power of up to 400 kW. ECR ion sources installed above ground will be used to provide highly charged ions, that will be transported into the linac tunnel approx. 10 m below ground. For the heaviest ions, two charge states will be accelerated to about 0.5 MeV/u using a room-temperature 80.5 MHz RFQ and injected into a superconducting cw linac, consisting of 112 quarter-wave (80.5 MHz) and 229 half-wavelength (322 MHz) cavities, installed inside 52 cryomodules operating at 2K. A single stripper section will be located at about 17 MeV/u (for uranium). Transverse focusing along the linac will be achieved by 9 T superconducting solenoids within the same cryostat as the superconducting rf accelerating structures. This paper describes the matured linac design, as the project is progressing towards a Department of Energy performance baseline definition in 2012. Development status of the linac subcomponents are presented with emphasis on the superconducting RF components.
FRIB, East Lansing, Michigan, USA
Superconducting quarter-wave resonators and half-wave resonators are being prototyped and fabricated at Michigan State University (MSU) in effort to support the Facility for Rare Isotope Beams (FRIB) project. FRIB requires a 200 MeV per nucleon driver linac, operating 345 resonators at two frequencies (80.5 and 322 MHz) and four betas (0.041, 0.085, 0.29, and 0.53). FRIB cavity development work is underway, with the prototyping of all four resonators, including helium vessel design, stiffening strategy, and tuner interface. In addition, the acquisition strategy for FRIB resonators is being finalized, and the technology transfer program is being initiated. The status of the resonator production effort will be presented in this paper, including an overview of the acquisition strategy for FRIB.
FRIB, East Lansing, Michigan, USA
A study has been initiated at Michigan State University (MSU) to relate the surface preparation of Superconducting Radio Frequency (SRF) resonators and surface particle counts, using niobium samples. During fabrication, undesired surface roughness can develop on the internal surfaces of the resonators. The final cavity finish will be product of material forming, machining, welding, chemistry, high-pressure rinsing, and handling of the niobium material. This study will document niobium samples treated with MSU standard processing procedures; first measuring the surface roughness, then polishing samples with defined techniques, processing, and measuring surface particle counts. The samples will include as received niobium, machined surfaces, welded surfaces, and surfaces with characterized surface imperfections (scratches).