Status and Plans of UK Undulator Prototyping R

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Status and Plans of UK Undulator Prototyping RD
Yury Ivanyushenkov for HeLiCal Collaboration

• ILC Positron source meeting
• 27th - 29th September 2006
• RAL

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HeLiCal Collaboration
CCLRC Technology Rutherford Appleton
Laboratory D.E. Baynham, T.W. Bradshaw, A.J.
Brummitt, F.S. Carr, Y. Ivanyushenkov, A.J.
Lintern, J.H. Rochford CCLRC ASTeC Daresbury
Laboratory and Cockcroft Institute A. Birch,
J.A. Clarke, O.B. Malyshev, D.J. Scott
University of Liverpool and Cockcroft
Institute I.R. Bailey, P. Cooke, J.B. Dainton,
L.J. Jenner, L.I. Malysheva University of
Durham, CERN and Cockcroft Institute G.A.
Moortgat-Pick DESY D.P. Barber, P. Schmid
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Scope

• ILC Undulator specification
• Working technical specification
• Undulator prototyping RD programme
• Full scale undulator module
• Plans

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ILC Undulator specification

• Electron energy 150 GeV
• Undulator period 10 mm
• Field on axis KxKy 1 or 10 MeV photon in
  first harmonic ?

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Working specification

• Undulator period as close as possible to 10 mm
• Field on axis to produce 10 MeV photons (first
  harmonic)
• Field homogeneity 1
• Vacuum bore to have beam stay clear of 4 mm gt
  about 5 mm for vacuum bore and about 6 mm for
  magnetic bore
• Superconductor (NbTi) working point about 80
  of short sample critical current.
• Module length 4 m

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Undulator prototyping RD goal

• Develop reliable magnetic modelling technique
• Develop undulator manufacturing technique
• Manufacture and test first full scale undulator
  module

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Magnetic modelling with Opera 2d and 3d

• Winding aspect ratio the highest field on
  axis is achieved with a rectangular winding with
  the smallest radial height to- length ratio
  (flat conductor). However, taking into
  consideration the peak field in the conductor, a
  square shape was found to be optimal.
• Winding current to produce 0.8
  T-field on axis a 1000 A/mm2 current density is
  required (winding - 4mm 4 mm winding
  internal diameter - 6 mm period - 14 mm)
• (Note What is the optimal current distribution
  in the conductor ?)
• Field on axis can be enhanced by the former
  poles made of magnetic material. The inclusion of
  magnetic material outside the winding also
  increases the field on axis.
• Peak field is about twice the field on the
  axis
• for the above configuration, even higher for
  undulator with iron poles and iron yoke.
• (Room for improvement Nb3Sn ?)
• Tolerance effects on central field value
  winding radius variation of 0.1 mm leads to 4.2
  change in the on axis field value, the changes
  induced by changing the winding period by 0.1 mm
  are at the level of 3.

Region with the highest peak field
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Magnetic modelling predictions
Conclusion so far Period of 10 mm means very
small bore -unpractical! Realistic figures Beam
stay clear 4 mm Vacuum bore - 5 mm Winding
bore - 6 mm Period - 11.5 mm
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Prototypes matrix
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Prototypes family
Please join us for Undulator RD Facility Tour
on Friday to learn more on manufacture technique
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Prototype I results
Very successful prototype Never quenched
Reaches the design field Quite good field
profile
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Prototype II results
Field on axis varies by -2 for 100 µm increase
in winding bore ? /- 1 variation in the
field translates into /- 50 µm precision in
winding bore for pitch 14 mm
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Prototype III results
Period 12 mm Winding bore 6.35 mm 7-Wire Ribbon 8
Layers Wire CuSc 1.351
Measured field 0.533 T (/- 0.4 St.Dev.,
/- 0.8 max)
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Prototype IV results
Measured field 0.91 T /- 1.6 St.Dev
Former Iron Pitch 12
mm Winding bore 6.35 mm Bore
4.5 mm Winding 7 wires
x 8 layers
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Prototypes III and IV effect of iron
Samples 1-3 080A16 Bright steel (BS970) Sample
4 unknown mild steel
Undulator geometry Period 12 mm Winding bore
6.35 mm Winding 8 layers of 7-wire ribbon Wire
current 200A
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Technology status

• Former manufacturing - developed techniques for
  machining formers in aluminium and iron
•               - accurate gun drilling of bore
•               - machining of iron spring
  configuration
•        - assembly procedure which can be
  extended to 2m coil module fabrication
• Coil winding technology
•                 - winding based on ribbon
  technique
• - winding machine
•                 - coil terminations
•                 - coil impregnation with epoxy
• Magnet testing and field measurements
•                 - field measurements - Hall probe
  movement and positioning at 4K
•                 - LabVIEW logging software

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Short prototypes summary
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Undulator 4m module

• The main features of the undulator module are
• The module will be made up of a magnet ( two
  sections), helium bath, thermal shield and a
  cryostat.
• The former which is 11.5mm pitch with a 6.35 DIA
  winding bore.
• The former will give 1747mm of magnet length.
• The overall length of the cryostat is 4m.
• The turret for the services will be in the centre
  of the cryostat.
• Cold mass is cooled by a cryocooler mounted in
  the tarret.
• Thermal shield is pre-cooled by liquid nitrogen
  to reduce overall cooling time

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Undulator 4m module Layout
He bath vessel
Thermal shield
Two sections of the undulator magnet
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Undulator 4m module Cold mass
Undulator magnet assembly
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Undulator 4m module More details
Turret region
Cryostat wall Thermal shield - He vessel -
Magnet connection
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Plans

• Complete the Helical Undulator R D Programme by
  November 2006
• Design, Manufacture and Test a 4m long Helical
  Undulator Module by end July 2007
• Complete conceptual design by October 2006
• First 2m-long magnet tested by March 2007
• Second magnet and cryostat manufactured by May
  2007
• Module assembly and cold test completed by end
  July 2007
• Note we are not planning to build a field
  measurement system for 4-m module -gt a proposal
  by ANL to build such a system looks very
  attractive and necessary -gt a formal
  collaboration with Argonne should probably start.

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Plans (2)

• Beam test of 4-m undulator module at Daresbury
  Lab fall 2007.
• Pre-production prototype 2008-09.
• Funds are requested, awaiting decision.