Superconducting Magnets/Light Sources

Paper Title Page
MPPT032 Construction and Performance of Superconducting Magnets for Synchrotron Radiation 2218
  • C.-S. Hwang, C.-H. Chang, C.-K. Chang, H.-P. Chang, C.-T. Chen, H.-H. Chen, J. Chen, J.-R. Chen, Y.-C. Chien, T.-C. Fan, G.-Y. Hsiung, K.-T. Hsu, S-N. Hsu, M.-H. Huang, C.-C. Kuo, F.-Y. Lin
    NSRRC, Hsinchu
  Two superconducting magnets, one wavelength shifter (SWLS) with a field of 5 T and one wiggler (SW6) with a field of 3.2 T, were constructed and routinely operated at NSRRC for generating synchrotron x-rays. In addition, three multipole wigglers (IASW) with fields of 3.1 T will be constructed and installed each in the three achromatic short straight sections. A warm beam duct of 20 mm inner gap and a 1.5 W GM type cryo-cooler were chosen for the SWLS to achieve cryogen-free operation. For the SW6, a cold beam duct of 11 mm inner gap was kept at 100 K temperature and no trim coil compensation is necessary for its operation. Meanwhile, no beam loss was observed when the SW6 was quenched. A cryogenic plant with cooling power of 450 W was constructed to supply the liquid helium for the four superconducting wigglers. The design concept, magnetic field quality, the commissioning results, and the operation performance of these magnets will be presented.  
MPPT033 Development of a Superconducting Helical Undulator for a Polarised Positron Source 2295
  • Y. Ivanyushenkov, F.S. Carr
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  • D.P. Barber
    DESY, Hamburg
  • E. Baynham, T.W. Bradshaw, J. Rochford
    CCLRC/RAL, Chilton, Didcot, Oxon
  • J.A. Clarke, O.B. Malyshev, D.J. Scott, B.J.A. Shepherd
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • P. Cooke, J.B. Dainton, T. Greenshaw
    Liverpool University, Science Faculty, Liverpool
  • G.A. Moortgat-Pick
    Durham University, Durham
  A method of producing a polarised positron beam from e+e- pair production in a target by circularly polarised ?-radiation is being investigated. Polarised photons are to be generated by the passage of a high energy electron beam (250 GeV as anticipated in the International Linear Collider - ILC) through a helical undulator. For production of 20 MeV photons, an undulator with a period of 14 mm, a bore of approximately 4 mm and magnetic field on axis of 0.75 T is required. First prototypes have been constructed using both superconducting and permanent magnet technologies which are capable of producing the necessary magnetic field configuration in the undulator. This paper details the design, construction techniques and field measurement results of the first superconducting prototype and compares the results with simulation.  
MPPT034 Field Modelling for the CESR-c Superconducting Wiggler Magnets 2336
  • J.A. Crittenden, A.A. Mikhailichenko, A. Temnykh
    Cornell University, Department of Physics, Ithaca, New York
  • E.N. Smith, K.W. Smolenski
    Cornell University, Ithaca, New York
  Funding: National Science Foundation.

Superconducting wiggler magnets for operation of the CESR electron-storage ring at energies as low as 1.5 \gev have been designed, built and installed in the years 2000 to 2004. Finite-element models of field quality have been developed, various sources of field errors investigated and compared to field measurements. Minimization algorithms providing accurate analytic representations of the wiggler fields have been established. We present quantitative descriptions of field modelling, of measured field quality and of the accuracy achieved in the analytic functions of the field.

MPPT035 Magnetic Field Analysis of Superconducting Undulators with Variable Field Polarization 2410
  • S.H. Kim
    ANL, Argonne, Illinois
  Funding: Work supported by the U.S. Department of Energy under Contract No. W-31-109-ENG-38.

An undulator with double-helix coils on a cylindrical beam tube is the classical method of producing a helical magnetic field. This type of device, however, can produce only circularly polarized radiation and has limited horizontal aperture for beam injection. A planar superconducting undulator SCU) unit of helical field, which generates horizontal and vertical fields perpendicular to the beam direction, is inserted in between the magnetic poles of a vertical-field unit. This paper analyzes the magnetic fields and a scaling law of the SCU. The angle of the coil windings for the inserted unit is analyzed to maximize the horizontal field Bx. The range of the optimum rotation angle, for the range of gap/period ratio 0.1 - 0.6, is calculated to 30 - 40 degrees.

MPPT036 R&D of Short-Period NbTi and Nb3Sn Superconducting Undulators for the APS 2419
  • S.H. Kim, C. Doose, R. Kustom, E.R. Moog, I. Vasserman
    ANL, Argonne, Illinois
  Funding: Work supported by the U.S. Department of Energy under Contract No. W-31-109-ENG-38.

A superconducting undulator (SCU) with a period of 14.5 mm is under development at the Advanced Photon Source (APS). The undulator is designed to achieve a peak field on the beam axis of 0.8 T with an 8 mm pole gap and an average current density of 1 kA/mm2 in the NbTi coil. A 22-period half-section of a SCU has been fabricated. The SCU half-section was charged up to near the average critical current density jc of 1.4 kA/mm2, and the stability margin was measured by imposing external heat fluxes on the coil at 4.2 K in pool boiling LHe. The magnetic fields along the midplane of the SCU were measured using a Hall-probe field-mapping unit installed in a vertical dewar. The first test of a Nb3Sn short-section SCU reached an average current density of 1.45 kA/mm2, slightly higher than the jc for the NbTi SCU.