Permanent Magnet Option for ILC Final Doublet Quads and Tail Folding Octupole

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Permanent Magnet Option for ILC Final Doublet
Quads and Tail Folding Octupole

• Y. Iwashita, T. Mihara, S.Nakamura,
• M. Ichikawa, Y. Tajima, Kyoto University
• M.Kumada, NIRS
• C.M. Spencer, SLAC

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Adjustable Permanent Magnet QuadrupolePrototype
for 20mr Xing Angle
Permanent Magnet (NEOMAX38AH)
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Prototype Magnet
Extra beam hole
Inside View of Outer Ring
Inner Ring
Base plate
Before assembly
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Magnetic Center Movement
The cm values show the Switched-On-Length
The center moves several µm for 20 strength
change. See http//accelconf.web.cern.ch/AccelConf
/l04/PAPERS/TUP81.PDF (LINAC04)
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Recent Modification
Demonstrate a higher field gradient by reducing
the bore size from ø20mm down to ø15mm.
Temperature compensation of the inner ring 1 mm
(left) and 1.6 mm (right) MS-1 trapezoidal plates
are seen in a 2cm space between magnets.
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Longitudinal Distribution

• Vertical component By measured along Z by a
• Group3 Tesla meter.
• dz 2mm,
• z 0 380mm
• dx, dy 2mm

Bore ø15mm
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Longitudinal Distribution
Bore ø15mm
All OFF
All ON
T/m
T/m
Centroid
Centroid
Z mm
Z mm
Almost flat Gmax 190T/m Gmin 29T/m
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SWL 4cm
SWL 8cm
Centroid
Centroid
T/m
T/m
Centroid
Centroid
Z mm
Z mm
Gradient is high at ON region. Magnet gaps of the
inner ring affects the distribution.
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Integrated Strength (GL) ?G dz
40 35 30 25 20 15 10 5
T
GL value is proportional to the SWL GLmax 38
T GLmin 5.9T _at_ø15,L23cm
SWL cm
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Magnetic field centroid
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Cases of only 8cm (entrance) ON or only
4cm(exit) ON shows the maximum and minimum.
mm
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Centroid location as a function of SWL
The excursion of the centroid is almost half of
its length it can be reduced by using a couple
of PMQs back to back.
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Required specs for Final Focus
Variable PMQ will generate 1400kG/m, but 14mrad.
case needs more study.
Brett Parker's sketch of how they be placed as
sc. quads
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Demagnetization by Radiation
Energy deposit
Demagnetization by 14MeV neutron
T. Kawakubo, et al., The 14th Symposium on
Accelerator Science and Technology, Tsukuba,
Japan, November 2003, pp. 208-210, in Japanese,
http//conference.kek.jp/sast03it/WebPDF/1P027.pd
f
very preliminary results by T.Abe (university of
Tokyo), in private communication
Continuous 1mo.(2.6x106s) operation may cause
about 0.01 of (reversible?) demagnetization on
NEOMAX 32EH. (1 for 10 years) ... needs more
info.
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PM-Octupole for Tail Folding
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PM-Octupole for tail-folding
Bore ø32, Size ø150 for ATF2
ILC Baseline Sc design 0.5T_at_pole tip, 1TeVCM
PMO can be strong shorter in length.
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Mutlipole components
Rotation of the ring may be analog not digital
way.
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Reduced skews
Skew components can be canceled if two outer
rings are incorporated and rotated in opposite
direction.
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Summary

• Adjustable PMQ realizes 140T/m_at_ø20mm
• The excursion of lens center was measured.
• New config. may be possible for smaller cross
  section(Needs more idea and study including
  lattice design)
• Demagnetization seems small (1 for 10
  years?)maybe OK even if 10 times more, but needs
  more info.
• Octupole for tail folding?
• Will fabricate one model (Quad or Octupole)
  may be tested in ATF2

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