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US LHC Accelerator Research Program
bnl - fnal- lbnl - slac
Simplified RD models for the LHC Dipole-First
IR LARP Collaboration MeetingNapa, October
19-21, 2004 Gian Luca Sabbi
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Dipole First IR

• Potential advantages
• - reduced number of long-range beam-beam
  collisions
• beam on axis local field error correction in
  the IR quads
• D1 Dipole requirements
• need to separate and accommodate both beams 15
  T, 120 mm bore
• need to withstand large power deposition from
  secondaries
• Magnet RD issues
• - Operating field, forces and stresses are
  beyond the state of the art
• - Mitigation of the radiation load ? split coils
  with open mid-plane

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Sample Coil Geometry Parameters

• Features
• Intercepts to mitigate stress accumulation (Stres
  s in each block lt 150 MPa)
• Conductor grading for magnetic
  efficiency (Dipole field 15 T)

Stored energy LARP 3.9 MJ/m RD3 1.2
MJ/m HD-1 0.6 MJ/m Inductance LARP 90
mH/m RD3 21 mH/m HD-1 11 mH/m
Field quality optimize at beam radius along the
horizontal axis?
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Three-year Plan (LAPAC, June 04)
Examples of possible dipole tests in FY05-07
1. Sub-scale coils in open mid-plane
structure 2. HD1 coils in open mid-plane
structure 3. Large Dipole 1 - LD1
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Sub-scale Test (LAPAC, June 04)
First step towards open mid-plane dipole
mechanical design

• Design to address the design issues of the
  full-scale dipole
• ? Open mid-plane
• ? Coil impregnated in the structure (also
  relevant to quad)
• Coil displacement/gaps due to low/no pre-stress
• Several tests with changes in force
  configuration
• Joint effort LBNLBNL
• Affordable, fast turnaround, but relatively low
  field/forces

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HD1 with Open Mid-plane

• Significantly increased field, forces and
  stresses with respect to sub-scale
• Increased structure cost, still affordable due
  to use of HD1 coils
• Test is focused on the structure (coil
  performance is already demonstrated)

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LD1 Features Objectives

• Approach scale HD2-type coil and structure to
  full D1 aperture
• Design features
• Target field and aperture 15-16 T 150 mm x 100
  mm clear bore
• Strand 1 mm diameter (new OST with increased
  sub-elements)
• Iron insert in pole module, tilted ends in
  midplane module
• No conductor at the mid-plane (?3 mm)
• Moderate field quality
• Objectives
• 1. fabricate and test a set of full field, full
  aperture coils
• 2. Design/test traditional structure to
  establish coil performance
• 3. Test coils in open mid-plane structure

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Design Parameters
Harmonics (15 T, 50 mm radius)
All bn lt 20 units (0.2)
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Lorentz Forces and Stresses

• Layer 1
• Fx 5.6 kN/mm
• Pre-stress 115 MPa
• Fy - 2.1 kN/mm
• Pre-stress 45 MPa
• Layer 2
• Fx 8.9 kN/mm
• Pre-stress 165 MPa
• Fy - 5.1 kN/mm
• Pre-stress 100 MPa

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Support Structure (Phase I)
Aluminum shell Thickness 100 mm Stress
(293K) 50 MPa Stress (4.3K) 170 MPa Iron
yoke Outer diameter 1.6 m Assembly
bladders Width 100 mm Pressure 50
MPa Bore Width 150 mm Height 100 mm
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Bore Stress
Cool-down
Nominal field (15 T)
Peak stress 850 MPa
Peak stress 600 MPa
Bore stress is compatible with the yield limit
for Nitronic 40 (gt 1200 MPa) Further optimization
is required to decrease the coil stress (see next
slide)
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Coil Stress
Full pre-stress delivered, to prevent separation
from the pole at high field Further optimization
is required to decrease the peak coil stress
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Quench Protection

• Quench heater design
• Stainless steel (23 mm thick) with distributed
  Cu 12 mm thick foil
• Heater is contained between two layers of Kapton
  
• Active sections are 210 mm long, 42 of total
  magnet length
• Two Heater Power Supplies (450V, 24mF)
• Each coil modules has one layer powered by each
  of the supplies

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Summary
The Scream (LARP)
The Scream (Munch)