Permanent Magnets

Paper Title Page
MPPT025 Field Quality and Magnetic Center Stability Achieved in a Variable Permanent Magnet Quadrupole for the ILC 1913
  • Y. Iwashita, T. Mihara
    Kyoto ICR, Uji, Kyoto
  • M. Kumada
    NIRS, Chiba-shi
  • C.M. Spencer
    SLAC, Menlo Park, California
  Funding: Work supported in part by Department of Energy contract DE–AC03–76SF00515 and by the Ministry of Education, Science, Sports and Culture, Japan, Grant-in-Aid for Scientific Research (A) 14204023.

The precise tolerances on the last two quadrupoles before the interaction point of the proposed, superconducting e+e- collider (ILC) have not been determined yet. These quads will be aligned with a beam-based alignment (BBA) process during which their integrated strengths will be decreased by 20%. Their magnetic centers must move by less than a few microns during the BBA else a systematic error will be introduced, yielding an increase in the beam spot size. These strong quads must be small to fit in the tight space. A compact, variable, superstrong permanent magnet quad (PMQ) has been fabricated and tested. The PMQ has inner and outer rings of NEOMAX; the outer ring is subdivided along its length and each section can rotate. By rotating different lengths one can vary the integrated strength in small steps. Because of the fixed inner ring and tight mechanical tolerances, the sensitivities of the magnetic center and pole angles to the rotation of the outer rings are largely suppressed. Measurements of the PMQ will be presented, plus how observed small center and angle shifts were further reduced by adjustments to the stopping angles of the rotating rings and by shimming these rings.

MPPT026 Insertion Device Upgrade Plans at the NSLS 1949
  • T. Tanabe, A. Blednykh, D.A. Harder, M. Lehecka, G. Rakowsky, J. Skaritka
    BNL, Upton, Long Island, New York
  This paper describes plans to upgrade insertion devices at the National Synchrotron Light Source (NSLS), Brookhaven National Laboratory, U.S.A. The aging wiggler (W80) at X25 is being replaced by a 1 m long in-vacuum mini-gap undulator (MGU-18) optimized for a dedicated macromolecular crystallography program. A new, 1/3 m long, in-vacuum undulator (MGU-13.5), will be installed between a pair of RF cavities at X9, and will serve a new beamline dedicated for small angle x-ray scattering (SAXS). Both MGU’s will have provision for cryocooling the NdFeB hybrid arrays to 150K to raise the field and K-value and to obtain better spectral coverage. Design issues of the devices and other considerations, especially magnetic measurement methods in low temperature will be discussed.  
MPPT027 Three-Dimensional Design of a Non-Axisymmetric Periodic Permanent Magnet Focusing System 1964
  • C. Chen, R. Bhatt, A. Radovinsky, J.Z. Zhou
    MIT/PSFC, Cambridge, Massachusetts
  Funding: Work supported by the MIT Deshpande Center for Technological Innovation, the U.S. Department of Energy, High-Energy Physics Division, Grant No. DE-FG02-95ER40919, and the Air Force Office of Scientific Research, Grant No. F49620-03-1-0230.

A three-dimensional (3D) design is presented of a non-axisymmetric periodic permanent magnet focusing system which will be used to focus a large-aspect-ratio, ellipse-shaped, space-charge-dominated electron beam. In this design, an analytic theory is used to specify the magnetic profile for beam transport. The OPERA3D code is used to compute and optimize a realizable magnet system. Results of the magnetic design are verified by two-dimensional particle-in-cell and three-dimensional trajectory simulations of beam propagation using PFB2D and OMNITRAK, respectively. Results of fabrication tolerance studies are discussed.

MPPT029 Performance of an Adjustable Strength Permanent Magnet Quadrupole 2071
  • S.C. Gottschalk, T.E. DeHart, K.W. Kangas
    STI, Washington
  • C.M. Spencer
    SLAC, Menlo Park, California
  • J.T. Volk
    Fermilab, Batavia, Illinois
  Funding: Department of Energy Grant DE-FG03-01ER83305.

An adjustable strength permanent magnet quadrupole suitable for use in Next Linear Collider has been built and tested. The pole length is 42cm, aperture diameter 13mm, peak pole tip strength 1.03Tesla and peak integrated gradient * length (GL) is 68.7 Tesla. This paper describes measurements of strength, magnetic centerline and field quality made using an air bearing rotating coil system. The magnetic centerline stability during -20% strength adjustment proposed for beam based alignment was < 0.2 microns. Strength hysteresis was negligible. Thermal expansion of quadrupole and measurement parts caused a repeatable and easily compensated change in the vertical magnetic centerline. Calibration procedures as well as centerline measurements made over a wider tuning range of 100% to 20% in strength useful for a wide range of applications will be described. The impact of eddy currents in the steel poles on the magnetic field during strength adjustments will be reported.

MPPT030 Magnetic and Engineering Analysis of an Adjustable Strength Permanent Magnet Quadrupole 2122
  • S.C. Gottschalk, D.J. Taylor
    STI, Washington
  Funding: Department of Energy grant DE-FG03-01ER83305.

Magnetic and engineering analyses used in the design of an adjustable strength permanent magnet quadrupole will be reported. The quadrupole designed has a pole length of 42cm, aperture diameter 13mm, peak pole tip strength 1.03Tesla and peak integrated gradient * length (GL) of 68.7Tesla. Analyses of magnetic strength, field quality, magnetic centerline, temperature compensation and dynamic eddy currents induced during field adjustments will be presented. Magnet sorting strategies, pole positioning sensitivity, component forces, and other sensitivity analyses will be presented. Engineering analyses of stress, deflection and thermal effects as well as compensation strategies will also be shown.