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cryogenics

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MO3002 Overview of TEM-Class Superconducting Cavities for Proton and Ion Acceleration linac, proton, ion, vacuum 23
 
  • M. P. Kelly
    ANL, Argonne, Illinois
  Superconducting (SC) TEM-class cavities have been developed at laboratories and institututions worldwide for cw and pulsed proton and ion linac applications. New geometries spanning nearly the full velocity range from 0.1 < v/c < 0.8 include co-axial quarter- and half-wave and single- and multi-spoke cavities. Optimized designs have large beam acceptance, high shunt impedance and good microphonics properties. Rapidly evolving and improving clean surface processing techniques have been applied to TEM cavities where achieved surface fields and rf losses are comparable to the best results presently achieved in elliptical cavity designs. Recent results for a three-spoke cavity following hydrogen degassing after fabrication show very low rf losses even at high accelerating fields and now open the possibility for substantially reduced effective cryogenic load in 2 Kelvin, rather than the historically-used 4 Kelvin, operation. At present performance levels, SC TEM-class cavities constitute the technology of choice for most ion linac applications requiring cavities up to or beyond 60 percent of the speed-of-light.  
 
MOP033 The Operation Concept of SARAF controls, instrumentation, target, radiation 109
 
  • I. Mardor, D. Berkovits, Y. Grof, H. Hirshfeld, A. Nagler
    Soreq NRC, Yavne
  • O. Heber
    Weizmann Institute of Science, Physics, Rehovot
  • C. Piel
    ACCEL, Bergisch Gladbach
  The Soreq Applied Research Accelerator Facility (SARAF) is a 5 - 40 MeV, 0.04 -2 mA proton/deuteron RF superconducting linear accelerator, which is under construction at Soreq NRC and is planned to start generating a beam by the end of 2010. SARAF will be a multi-user facility, whose main activities will be neutron physics and applications, radio-pharmaceuticals development and production, and basic nuclear physics research. The operational concept of SARAF will be ‘one target at a time’ and during irradiation, appropriate shielding will enable preparation and maintenance at other stations. This paper presents the planned facility operation program, the planned operations group, the location and layout of the main control room and the architecture of the main control system, including its interfaces with safety and applications. Emphasis is given to the design considerations for each of the discussed subjects.  
 
TUP025 Optimization of Surface Treatment of High-Gradient Single-Cell Superconducting Cavities at KEK superconductivity, vacuum, pick-up, electron 299
 
  • F. Furuta, Y. Higashi, T. Higo, I. H. Inoue, S. Kazakov, H. Matsumoto, Y. Morozumi, R. S. Orr, T. Saeki, K. Saito, M. Satoh, K. Ueno, H. Yamaoka
    KEK, Ibaraki
  We have continued the study of a series of single cell superconducting cavities at KEK. These tests are aimed at establishing a prescription for a surface treatment that would reliably allow cavities to reach gradients in excess of 45 MV/m in vertical tests. The cavity profiles were all of the KEK Low Loss design, and were fabricated from deep drawn Niobium half shells using electron beam welding. The cavity initial surface preparation followed an established KEK procedure of centrifugal barrel polishing, high temperature annealing, light chemical polishing, electropolishing. and final a high pressure water rinse. Early results from this series test demonstrated that reaching gradients as high as 50 MV/m is feasible. However, the initial yield was of order 50%. In this paper we will discuss our studies of further improvement of the surface treatment aimed at increasing the yield.  
 
TUP029 Performance and Early Operating Experience with the ISAC-II Cryogenic System linac, vacuum, ion, controls 306
 
  • R. E. Laxdal, W. Andersson, I. Sekachev, G. Stanford
    TRIUMF, Vancouver
  A 500 W class refrigerator has been installed and commissioned at TRIUMF to cool the new 20MV superconducting linac. The refrigerator liquifies helium into a common supply dewar. The dewar feeds a common cold manifold and the five cryomodules are fed via parallel cold distribution circuits. The system operates at 4.5K. Measurements have been done to estimate the static loads of the cryomodules and the distribution system and to characterize plant performance. The paper will include a system description, performance results and early operating experience.  
 
THP052 Tests Results of Beta 0.12 Quarter-Wave Resonator for the SPIRAL2 Superconducting Linac linac, controls, heavy-ion, vacuum 698
 
  • G. Olry, S. Blivet, S. Bousson, T. Junquera, J. Lesrel, fl. Lutton, G. Martinet, H. Saugnac
    IPN, Orsay
  New developments and tests have been carried out, at IPN-Orsay, on high β = 0.12, 88 MHz superconducting Quarter Wave Resonators. These resonators will be installed in the high beta section of the LINAC driver. RF tests results of the prototype cavity are reported. The fabrication of 2 pre-series cavities and their cryomodule is in progress in order to be ready for high power RF tests at 4.2 K at the beginning of 2007.  
 
THP053 Simulations and Optimizations of a New Power Coupler for 3.9-GHz Superconducting Cavities at Fermilab simulation, electron, coupling, impedance 701
 
  • J. Li, I. G. Gonin, T. K. Khabiboulline, D. O. Olis, N. Solyak
    Fermilab, Batavia, Illinois
  • T. Wong
    Illinois Institute of Technology, Chicago, Illinois
  3.9 GHz third harmonic superconducting cavities have been used to increase the peak bunch current and to compensate for non-linear distortions in the longitudinal phase space due to sinusoidal 1.3 GHz accelerating cavity voltage. The power coupler is one of the important and complicated components of the third harmonic system for the TTF3 project. From electromagnetic, multipacting, and thermal simulations of the power coupler, optimized designs have been achieved, enabling one to minimize or eliminate potential problems in advance. This paper presents our recent work on simulation and optimization of the power coupler.  
 
THP054 Spoke Cavity Developments for the EURISOL Driver vacuum, proton, linac, diagnostics 704
 
  • S. Bousson, J.-L. Biarrotte, fl. Lutton, G. Olry, H. Saugnac, P. Szott
    IPN, Orsay
  EURISOL is the next generation of Radioactive Ion Beam (RIB) facility which aims at the provision of high intensity beams of radioactive nuclei with variable energy, from a few keV to greater than 100 MeV per nucleon, at an intensity several orders of magnitude higher than those currently available. The driver of EURISOL has to accelerate protons at a final energy of 1 GeV and 5 mA current, but also deuterons at 200 MeV (total energy). For the intermediate energy part of the driver, a solution based on superconducting (SC) spoke cavities is under study at the IPN Orsay laboratory. In this paper are presented the results of beam dynamics simulations for the linac, experimental results on the β = 0.15 spoke cavity, as well as achievements on the power coupler and cold tuning system. A new horizontal cryostat for performing a test of a fully equipped spoke cavity is detailed and an optimized design for a new β ~0.35 spoke prototype is also presented.  
 
THP060 Capture Cavity II at Fermilab vacuum, klystron, resonance, instrumentation 719
 
  • T. W. Koeth
    Rutgers University, The State University of New Jersey, Piscataway, New Jersey
  • J. Branlard, R. H. Carcagno, B. Chase, P. Czarapata, H. Edwards, R. P. Fliller, C. M. Ginsburg, B. M. Hanna, A. Hocker, A. Klebaner, M. J. Kucera, M. McGee, D. F. Orris, P. S. Prieto, J. Reid, J. K. Santucci, W. M. Soyars, C.-Y. Tan
    Fermilab, Batavia, Illinois
  Capture Cavity II is a 9-cell high gradient TESLA Superconducting cavity intended to upgrade the existing Fermilab Photoinjector electron beam energy from 15MeV to 40Mev. DESY provided the cavity which performed to 33MV/m. Beam tube component preparation and installation onto the cavity was completed at DESY. The cavity was shipped to FNAL under vacuum. Installation and testing of this cavity has provided an opportunity to demonstrate Fermilab’s SCRF High Power Testing infrastructure. We report on the high power RF tests performed with Capture Cavity II at both 4.5K and 1.8K, Cryogenic System Performance, Piezo Electric based fast tuner, and low level RF control.  
 
THP067 Status of the Tuner for the 19-Cell Superconducting CH Prototype Cavity simulation, radio-frequency, vacuum, linac 737
 
  • C. Commenda, H. Liebermann, H. Podlech, U. Ratzinger, A. C. Sauer
    IAP, Frankfurt-am-Main
  • K. Dermati
    GSI, Darmstadt
  The radio frequency tuning of the multi-cell superconducting CH structure for beta equal to 0.1 is investigated for a 19-cell niobium cavity operated at liquid helium temperature. By applying external mechanical forces the deformation of the structure is studied and the resulting change in frequency is analysed. The ruling equations of elasticity and the electromagnetic eigenvalue problem are solved by using commercial finite element tools. The quantitative results form the basis of an optimized tuning device. In order to guarantee a long lifetime of the cavity, fracture criteria are defined to avoid mechanical damage. Wherever possible the results are compared with experimental data obtained from measurements performed on the first CH prototype developed at the Institute of Applied Physics at Frankfurt. In addition a fast piezo device will be integrated into the slowly acting mechanical tuner. The whole system will operate in an existing horizontal cryostat for testing purposes.  
 
THP082 Industrialization of TESLA-Type SRF Technology at ACCEL vacuum, controls, electron, monitoring 773
 
  • M. Pekeler, S. Bauer, H. Vogel, P. vom Stein
    ACCEL, Bergisch Gladbach
  In the last 15 years the worldwide TESLA collaboration under the leadership of DESY performed successful developements of SRF technology for possible use in a future international linear collider (ILC). Today this technology is also the baseline for other demanding projects like the European X-FEL at DESY site, 4GLS at Daresbury, BESSY FEL, Cornell-ERL, FEL at Peking University and others. Through all these years ACCEL has followed and supported this tremendous developement by producing and processing SRF cavities, couplers and complete accelerator modules. The current ability and future prospects of ACCEL for manufacturing and processing such key components as well as turnkey SRF modules with guaranteed performance for such projects are described.