Nb3Sn LHC IR Quad Magnet Workshop

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Nb3Sn LHC IR QuadMagnet Workshop FermiLab
August 4-6, 2003Shlomo Caspi
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Conceptual Design
Gss270 T/m 20kA 90mm bore
Coil
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Two Sub-assemblies
Coil Pack low pre-stress
Structural Pack
Aluminum Shell
Iron Pads
Iron Yoke
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Finite element model 4 Steps

1. Bladders pressurized
2. Keys inserted, bladder deflated
3. Cool-down
4. Lorentz forces 5 MN/m

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• Short Term Goals

• Complete one full design iteration
• Cross-section, Ends, Structure, Assembly
  procedure etc
• Completed a 3D CAD model
• Completed a 3D ANSYS model - structural and
  thermal
• Build and test a 1 m long mechanical model
• 1m Aluminum shell beginning of August
• 4 way Iron yokes end of August
• Pads cost estimate
• Inner tube

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Mechanical Model- Final assembly
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• Short Term Goals Continue

• Instrument inner tube and outer shell with
  strain-gauges
• Measure stress-strain relation between outer
  shell and inner tube as a function of bladder
  pressure.
• Measure inner tube (id) displacements as a
  function of key size (full symmetry) systematic
  errors
• Measure inner tube (id) displacements as a
  function of different key size (random size)
  random errors
• Repeat measurements at room temperature and 4.2K

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• Long Term Goals

• Replace inner tube with current NbTi coils from
  Fermilab
• Replace NbTi coils with Nb3Sn coil

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• What have we done so far

• Several cross sections
• A CAD solid model
• First iteration in Tosca
• Several 2D iterations in ANSYS
• First 3D iteration in ANSYS

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3D - ANSYS
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Layer 1 Time Step
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Lorentz Load - Layer 1
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Azimuthal Stress in Shell, mu0
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• Layer 1 - Uz

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Mechanical Summary

• Inflatable bladders
• internal press

• Aluminum Shell
• Reduces assembly pre-stress
• Monitor average coil pre-stress.

• Interference Keys
• No spring back loss
• Never overstress coil
• Allow bladder removal
• Pre-stress gain during cool-down 100 Mpa
• Confine high tolerances to key regions
• Allow adjustment of magnetic errors