FRIB, East Lansing, Michigan, USA
The driver linac for the Facility for Rare Isotope Beams (FRIB) requires superconducting Half Wave Resonators to accelerate ions to 200 MeV per nucleon. The Fundamental Power Coupler (FPC) is designed to deliver up to 14 kW of RF power at 322 MHz to the resonator and the beam in CW, and to increase the resonator’s control bandwidth for stable operation. With the resonator over-coupled, the mismatch creates a standing wave in the FPC and transmission line downstream of the circulator. The FPC includes an alumina vacuum barrier to allow the resonator to be under ultra-high vacuum. The FPC also serves as a thermal break between the room-temperature transmission line and the resonator at 2 K, with thermal intercepts designed to minimize the heat load to the cryoplant. The FPC design allows for some variation in the coupling, in case a larger bandwidth is needed to mitigate microphonic disturbances. The RF and mechanical design of the coupler and conditioning stand will be reviewed, and the results of high power RF conditioning and testing will be presented.
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
Michigan State University is developing and testing quarter wave resonators for a superconducting linac which will be used to reaccelerate exotic ions to 3 MeV per nucleon or higher (ReA3). Eight quarter wave resonators with an optimum velocity of β = v/c = 0.085 and a resonant frequency of 80.5 MHz are required for the third cryomodule, which will complete the first stage of the reaccelerator linac. Approximately 100 additional β = 0.085 resonators of the same design will be required for the Facility for Rare Isotope Beams (FRIB). Results of Dewar testing to characterize the RF performance of the resonators will be presented in this paper.