DESIGN STUDIES IR Magnet Design

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DESIGN STUDIESIR Magnet Design

• P. Wanderer
• LARP Collaboration Meeting
• April 27, 2006

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Thanks

• Thanks to Paolo, Giorgio, and Vadim, who prepared
  summaries of their work and many of the following
  slides.

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Topics

• 1 Analysis and comparison of IRQ based on
  shell-type and block-type coils (Ferracin, Maura
  Monville N. Mokhov)
• 2 Analysis of a 110-mm shell-type IR quads with
  different supporting structures (Ambrosio)

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Topics

• 3 Analysis of aperture and field quality
  limitations for double-bore IR Quads (Vadim
  Kashikhin)
• 4 Field quality analysis and error tables for
  Nb3Sn IRQ (Kashikhin, Zlobin)

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1 Compare block, shell quads

• Status For a reasonable set of IR quad
  requirements, a block quad was developed. The
  mechanical and magnetic properties of this quad
  and a shell quad which met the same requirements
  have been compared.
• Next Study response of these quads to IR
  radiation, iterate designs.

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Shell-type vs. block-type

• Previous work V.V. Kashikhin, et al., 2nd
  generation LHC IR quadrupoles based on Nb3Sn
  racetrack coils, EPAC 2004.

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Upgrade scenario

• Phase 1 increase of luminosity with hardware
  changes only in the interaction regions
• ß 0.25 m
• s 2.185 mm
• Dtrip 78.5 mm
• 77 mm (T. Sen, et al., 2001)
• Increase the triplet magnet diameter
• Same gradient
• Gnominal 200 T/m
• Gshort sample 250 T/m
• L 4 - 5 x 1034 cm-2s-1
• O. Bruning, et al., LHC luminosity and energy
  upgrade a feasibility study, LHC Project Report
  626 (2002)

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Coil aperture and beam envelope

• Dtrip 78.5 mm

80mm
105mm
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Magnetic design gradient and field quality

• TQ-v1 cable (27 strands)
• Jc 3000 A/mm2
• 1.9 K
• Harmonics lt 0.05 at Rref

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Mechanical design support structure

• Aluminum shell
• Iron yokes
• Stainless steel pad
• Stainless steel poles
• Stainless steel mid-plane spacers
• Aluminum bore

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Mechanical analysis coil and bore stresses

• Bore stress lt 150 MPa (293 K, 4.3 K and
  excitation)

• Coil stress lt 170 MPa

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2 Study of different support structures in quads

• 110 mm aperture, shell-type, 228 T/m.
• Generic structures for high forces
• Not specific to a particular coil
• Two types of coil arrangements
• Four layers, all glued together (complete)
• Four layers, glued together in pairs (now
  starting)

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Structure for 4 layers as 1

• Needs solutions
• Very rigid structure ? ss collars (ss skin or
  Al skin with bladders keys)
• Extra coil support at midplane ? collar-yoke
  support only at midplane
• Yoke open when warm
• Stresses lt 150 MPa under all conditions ? dummy
  cable at midplane of outer coil

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Best solution up to now

• Yoke with gap at 45 deg.
• Open _at_ 300 K
• Closed at 4.2 K
• Closed at 228 T/m
• Gap control spacers
• 15 mm SS collar ring
• Collar-Yoke contact 0-6 deg.
• Outer shell
• 15 mm SS skin or
• 30 mm Al (bladders keys)

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3 Study double-bore quads

• Quads for dipole-first optics
• Two cases warm and cold iron
• 100 mm aperture, 205 T/m
• 194 mm beam separation
• Determine dynamic aperture (10-4 FQ)
• Achieving good FQ a challenge
• Correctors LHC baseline
• Results presented April 19.

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Warm yoke design

• Maximizing the aperture at the fixed nominal
  gradient and the beam separation distance brings
  the adjacent coils close to each other
• There is not enough space for a ferromagnetic
  screen of sufficient thickness to individually
  shield each coil and avoid mutual influence
• In the warm yoke design the ferromagnetic part
  was removed from the cold mass and the coils are
  of an unusual asymmetric type to achieve a good
  field quality.

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Cold yoke design

• It is possible to bring the iron closer to the
  coils in the cold yoke design that increases
  the gradient and eliminates the eccentricity
  forces between the coils and the yoke
• The yoke inner surface has to be optimized
  simultaneously with the coil geometry to achieve
  good geometrical field quality and correct the
  yoke saturation effect
• The coils are still asymmetric, but the degree of
  asymmetry is lower than in the warm yoke
  design
• The coil aperture limit is 100 mm for both
  designs.

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Field quality
Geometrical harmonics _at_half-aperture radius
LHC has correctors for b3, b4, and b6.
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2-in-1 quad good field region
Green 27 mm radius beam envelope Red warm yoke,
10-4 FQ Blue cold yoke, 10-4 FQ
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Comparison

• MQXB beam envelope (2x9?) 40 mm
• MQXB FQ (measured) at 40 mm 10-4
• 2-in-1 quads 10-4 region 54 mm
• LARP beam envelope (1.1x18?) 70(60) mm
• LARP beam envelope (18?) 64(54) mm

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4 Error tables

• Error tables will combine calculated and measured
  errors from magnets of different radii.
• Status underway. There are more magnets to
  measure this FY, so the database is still being
  expanded.