EMMA Magnet

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EMMA Magnet

• Neil Marks
• ASTeC
• Cockcroft Institute All-hands meeting
• 29 March 2007

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Acknowledgements

• With considerable thanks to
• Ben Shepherd
• Take Yokoi (Adams Institute)
• Neil Bliss
• Clive Hill,
• (who have done most of the work and produced most
  of the material that you are about to see).

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The EMMA Ring
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Early plan view of magnets in EMMA lattice
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EMMA Magnets Unusual Features

• magnets provide both dipole (bending) and
  quadrupole (focusing) field they are combined
  function magnets
• the quadrupole field is far stronger than the
  dipole field they are therefore displaced
  quadrupoles
• independent adjustment of the dipole and
  quadrupole field is required
• they are very short yoke lengths of 55mm and
  65mm of the same order as the inscribed radius
  all ends and no middle.

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EMMA F type Magnet
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EMMA D type Magnet
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Current Magnet Parameters.

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EMMA Cells in 3D
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Modelling carried out with CST EM Studio (3D code)
F magnet
D magnet
now with realistic steel details provided by
Tesla
Combined model
http//www.cst.com/
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Difference between separate and combined models.
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Field Clamps

• Tracking studies suggest that field clamps are
  needed
• Reduce the amount of field leaking into the long
  straight
• Symmetric or asymmetric?
• Occupy space and increase power demand

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Field Clamps

• Integral gradient reduced by 11 (F) 18 (D)
• Little effect on good gradient region
• No saturation in the clamp plate

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Field Clamps
Field at clamp reduced by 80 in each case
F magnet
D magnet
Difference between asymmetric and symmetric
windows is negligible
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Optimisation of gradient quality -tangent point
variation
QBD tangent point 10mm
tangent point 48mm
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Investigation of field quality in 2D in QF,
tangent at 45 mm (OPERA 2D).
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Results as Dg(x)/g(0) for QF, tangent at 45mm.
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Optimisation of integrated gradient quality-
variation of chamfer on pole ends
Angle can be adjusted to 45 used up to now
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Modelling in 3D using OPERA
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Variation of ?g(x).ds in QF between different
limits tangent at 11 mm, no chamfer.
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Further Work

• proceed with tender exercise for 2 prototypes
• continue with 3D work using both OPERA 3D and CST
  EM Studio
• proceed with detailed 3 D measurements of
  prototypes on delivery.