Boosters and Cavities
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PO10 Performance of ALPI New Medium Beta Resonators 73
 
  • A.M. Porcellato, F. Chiurlotto, M. De Lazzari, A. Palmieri, V. Palmieri, S. Stark, F. Stivanello
    INFN/LNL, Legnaro (PD), Italy
 
  All the Nb sputtered medium beta cavities installed up to the last year in ALPI were produced by upgrading of old previously Pb plated substrates. For the first time this year we had the opportunity to test on line four 160 MHz, β=0.11 QWRs which were designed and built in order to be Nb sputtered. These resonators were sputtered in between 2007 and 2008 and they were tested at low fields (up to 3 MV/m) just after their production when they showed Q-zero values exceeding 1xE9. They were then stored for about three years in plastic bags and installed in ALPI only this year. The on line tests that we performed after installation showed Q-zero values reduced of about a factor five with respect to the ones measured in laboratory. It is the first time we could pick out a Q deterioration caused by storage in air. So far we have not recognized any Q–degradation both when the sputtered cavities were maintained in vacuum for many years and also when they were open to air for a few weeks for cryostat maintenance. In such a case, as it happened in the maintenance of cryostat CR19 housing high beta resonators, we could instead find some improvements in the Q-curves.  
 
PO16 MULTIPHYSICS AND PRESSURE CODE ANALYSIS FOR QUARTER WAVE β=0.085 AND HALF WAVE β=0.29 RESONATORS 92
 
  • S.J. Miller, J. Binkowski, A. Facco, M.J. Johnson, Y. Xu
    FRIB, East Lansing, Michigan, USA
 
  Funding: U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
The driver linac design for the Facility for Rare Isotope Beams (FRIB) at Michigan State University (MSU) makes use of four optimized superconducting radio frequency (RF) resonators to accelerate exotic ions to 200 MeV/μ. The RF resonators were optimized using computer simulations for all expected physical encounters and corresponding electrical resonant frequency changes. Principal guidance from the ASME boiler and pressure vessel code (BPVC) were applied.
 
poster icon Poster PO16 [0.535 MB]  
 
WEC01 Production 72 MHz β=0.077 Superconducting Quarter-wave Cavities for ATLAS 174
 
  • M.P. Kelly, Z.A. Conway, S.M. Gerbick, M. Kedzie, R.C. Murphy, B. Mustapha, P.N. Ostroumov, T. Reid
    ANL, Argonne, USA
 
  A total of eight 72 MHz β=0.077 superconducting quarter-wave cavities have recently been completed at Argonne National Laboratory. Seven of these will installed into the ATLAS superconducting heavy-ion linac as part of a beam intensity upgrade, with one remaining for the purposes of continuing to push the performance limits in these structures. Cavities were fabricated using techniques adapted the worldwide effort push niobium cavities close to the material limits. Key developments include the use of electropolishing on the complete helium-jacketed cavity. Wire EDM has been used instead of traditional niobium machining in order to minimize performance limiting defects near the weld seams. Hydrogen degassing at 600C after electropolishing has also been performed. Initial test results show practical acceleration at 4 Kelvin with cavity voltages, Vacc>3 MV/cavity and at 2 Kelvin with Bpeak>120 mT and Vacc>5 MV/cavity.  
slides icon Slides WEC01 [2.843 MB]