Magnetic development at MSL

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Magnet development at MSL Anders Hedqvist och
Fredrik Hellberg
European XFEL
Part 2Undulator quadrupoles (Anders)
Part 1 Beam dump bending magnets (Fredrik)
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Part 1 Hybrid magnet

• Outline
• XFEL beam dump bending magnets
• Why hybrid magnets?
• Hybrid magnet configuration.
• Optimization of a Halbach hybrid magnet
• Comparison with a conventional electromagnet
• Questions to be adressed
• Summary

MSL Fredrik Hellberg Anders Hedqvist Håkan
Danared DESY Winfried Decking Joachim Pflüger
Michael Schmitz Bernward Krause Alexander
Petrov
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XFEL beam dump bending magnets
Beam energy 10-25 GeV (17.5 GeV nominal
energy) Pole gap 3 cm Length 2 x 5 m
Deflection 1?/m B-field in gap 0.58-1.46 T
(1.02 T at 17.5 GeV)

• Hybrid magnet
• Low power consumption
• Integrated safety feature

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XFEL beam dump bending magnets
Maxwell equation in integral form
Assume BBgapBsteal
?s?1000
lp2l2, lsl12l3
?p?1
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Characteristics simple hybrid dipole
Hybrid magnet is preferred for Phyb/Pem lt 1.
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C-hybrid dipole with rectangular blocks of PMM

• Optimize hybrid magnet
• 1.02 T (17.5 GeV) bias field
• use low amount of permanent magnet material
• have high dB/dI

a,c and d was adjusted to optimize the hybrid
magnet Calculations with 2D program Pandira
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Optimization of hybrid magnet
Goal Find a configuration with 1.02 T (17.5 GeV)
bias field that use low amount of PMM and has
high dB/dI (yellow).
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Comparison with conventional electromagnet
The hybrid magnet is better than a conventional
electromagnet at 11-25 GeV (Phyb/Pem lt 1).
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Questions to be adressed

• Can high production costs be returned by low
  power consumtion?
• Is the permanent magnet material resistant
  against neutron radiation from the beam dump?

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Radiation damage

• Hierarchy of radiation damage pgtdgtngtegt?
• Magnets exposed to 1015 neutrons/cm2
  backscattered from the beam dump after 15 years
  of operation.
• Neutron energy 0-100 MeV.
• Process of loss of magnetic flux is not known
  (transmutation, dislocation of atoms and
  localized heating). Measurement are needed.

• Problem Most measurements done at nuclear
  reactors 0-15 MeV (peak at 1 MeV).
• SmCo more resistant than NdFeB, but more
  expensive and weaker.
• So far, no definite conclusions can be made
  concerning how much the permanent magnet material
  will be demagnetized.

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Summary

• The alternative of using a hybrid magnet instead
  of a conventional electromagnet at the European
  XFEL beam dump has been evaluated.
• A Halbach type block configuration was optimized.
• It is possible to make a hybrid magnet that use
  no power at the nominal energy and less than a
  conventional electromagnet 10-25 GeV.
• We still have to determine if the hyrid magnet is
  a better alternative.