CLAS12 Solenoid Conceptual design and assembly procedure

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CLAS12 Solenoid- Conceptual design and assembly
procedure -
Volker D. Burkert Jefferson Lab
Superconducting Magnet Review, Jefferson Lab,
September 26-28, 2006
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Summary of Requirements

• Provide magnetic field for charged particle
  tracking for CLAS12 in the polar angle range from
  40o to 135o.
• Provide magnetic field for guiding Møller
  electrons away from detectors
• Operation of dynamically polarized target at
  5Tesla with field in-homogeneity of ?B/B lt 10-4
  in cylinder of 10cm x 3cm.
• Full coverage in azimuth for tracking
• Allow particle tracking and momentum analysis
• Sufficient space for particle identification
  through time-of-flight measurements.

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SOLENOID - Design Solution

• Solenoid magnet with central field of 5 Tesla and
  integrated field length of 1m.
• Double coil arrangement for optimized field
  shaping in center and field compensation outside
  magnet
• Warm bore with 78cm useable diameter for
  particle tracking and particle identification
• Little interference with detectors and solenoid
  field.

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CLAS12 - TOROID-SOLENOID
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CLAS12 - SOLENOID
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CLAS12 SOLENOID Coils
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Central Detector
CLAS12
(B0 5 T)
TOF light-guide
Cryostat vacuum jacket
SiliconTracker
Space for e.m. calorimeter
Main coil
Shielding coil
Central TOF
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SOLENOID Coil Shape
Quadrant of the coil
main winding
compensation winding
The design uses the laminar winding technique
which allows an arbitrary cross section of the
winding. Slots in the upper part of the main
winding provide the necessary field homogeneity
and limit the maximum field. The space of the
slot is used for the placement of structural
plates.
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SOLENOID Coil Segment
The turn insulation is dry fiberglass fabric.
Compression is much higher than in the torus
magnet, and we beware of new excitation source
origin, that is cracking of a bulk adhesive. Thin
adhesive layers do not crack.
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Solenoid Magnet
CLAS12
Main coil
Beam axis
Shielding coil

• The winding consists of multi-pancake blocks.
  Every pancake contains turns of both main and
  shielding parts.
• Structural sheets take up radial pressure. Axial
  pressure is redistributed among the pancakes and
  structural columns with thick plates.

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Solenoid Field Map
CLAS12
Field variation DB/B in center
Magnetic field in quadrant (Tesla)

• Magnetic field distribution

4.5
4.0
?B/B lt 10-4 in cylinder of 10cm length x 3cm
diameter, as required for dynamically polarized
target operation.
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SOLENOID - Main Parameters
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SOLENOID - Dimensions
Precision of area compensation - 7E-6
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SOLENOID Structural Members
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SOLENOID Magnetic Field Map
The FEM computation agrees with the Bio-Savart
computation
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Solenoid Field Map
CLAS12
Magnetic field in quadrant (Tesla)
Field variation DB/B in center
4.5
4.5
Bmax 8.08 Tesla, at winding Iop 2865 A,
operating current
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SOLENOID 2D Stress Analysis
Most of the structural elements have a big margin.
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SOLENOID 2D Strain Analysis
The maximum strain is about 1.0 mm. It is
acceptable.
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Solenoid Field Map
CLAS12
Field variation DB/B in center
Magnetic field in quadrant (Tesla)

• Magnetic field distribution

4.5
4.0
?B/B lt 10-4 in cylinder of 10cm length x 3cm
diameter, as required for dynamically polarized
target operation.
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Magnetic Field Forces in Main Coil
A - Magnetic Field at every turn B - Tangential
force per every turn C - Tangential force per
every pancake D - Axial Force per every turn E -
Axial Force per every pancake
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Magnetic Field Forces in Shielding Coil
A - Magnetic Field at every turn B - Tangential
force per every turn C - Tangential force per
every pancake D - Axial Force per every turn E -
Axial Force per every pancake
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