Status Report of the Superconducting CR Magnet System

1
Status Report of the Superconducting CR Magnet
System

• Qiuliang Wang
• 2005, June, 9-10
• GSI , Germany

2
Outline of the report

• ? INTRODUCTION
• ? CR superconducting magnet-Magnetic field
  Design
• ? Superconducting Coil Design
• ? Conductor design
• ? Magnetic field in superconducting coils
• ? Quench properties
• ? Stress analysis of superconducting coils
  
• ? Design of Cryostat for Collector Ring coils
• ? Configuration of Cryostat
• ? Cooling Way of Superconducting magnet
• ? Stress analysis for Cryostat and coil
  support
• ? Conclusions

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INTRODUCTION for Layout of the collector Ring
(CR)
CR magnet
4
Design Requirements for CR Dipole
5
Benchmark and raodmap for CR

• ? The CR dipole magnets superferric H-type with
  a large available aperture (140380 mm2).
• ? Their useful maximum magnetic field 1.6T.
• ? The RD work for the CR dipole magnet system

CR magnet preliminary design
CR Intermediate design
CR magnet Final Design
CR Engineering Design
Fabrication, assembly and Testing
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Preliminary Design of raodmap for CR

• ? Electromagnetic design Yoke, pole and coils
  parameters, window, coils structure and type
• ? Yoke and pole configuration and material,
  fabrication
• ? Superconducting coils and Cryogenic
• Conductor Design, Operating Current
  Operating Current Choice from Temperature Margin
  Point, Operating Current Choice from Mechanical
  Consideration, Dimensions Optimization,
  Configuration Choice, Force Interaction,
  Mechanical Considerations, Spatial Field
  Distribution, Manufacturing Route Winding,
  Insulating, Impregnation,Joints and Terminations,
  Instrumentation, Assembly
• ? Power Supply, Quench Detection and Protection
  Systems
• ? CR Main Instrumentation, CR Main Quality
  Assurance Procedures

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Intermediate Design of raodmap for CR-1

• ?Thermal Analysis Temperature Margin Calculation
• Pressure Rise
  Inside the Cryostat During Quench
• technology
  risk analysis, Analysis Conclusions,
• ?Quench Protection Protection Principle, single
  and series
• Protection
  Scheme Analysis, detection, instrument
  
• Spatial Field
  Distribution at mechanical error
• ? Structural Analysis Structural Evaluation,
  Model Description and Criteria
• Standard
  Model, Advanced Model, Helium vessel
• Equivalent
  Stresses, Cool Down Stresses
• Conductor
  Quench Stresses
• Deformed
  State, Shear Stresses, friction
• ? Cryogenic Scheme Cryogenic Operating
  Requirements,Steady State Load
• 
  Refrigeration Load, Ring cryogenic system
• Cryogenic
  Losses Thermal Radiation, Current Leads
• Supports,
  Cool Down, Normal Operation

8
Intermediate Design of raodmap for CR-2

• ? Winding Scheme Requirements, Spool Mounting
  Vehicle, Conductor Cleaning,
• Bending
  Process, Coil Winding Jig, Epoxy, Turn Table
• Winding
  Fastening Units, Layer Transition
• Turn-to-turn
  and Layer-to-layer Spacer Insertion
• Conductor
  Forming for Coil, Termination, System Control,
• Insulation
  test, RT and CT.
• ? Yoke and Pole Yoke material, Yoke punching
  and error control, size
• Yoke
  assembly, yoke connect with cryogenic system,
• Yoke
  adjustment and field quality.
• ? System test Test flow
  chart....................

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To be continuous hard work and
breakthrough ..... ...... CR Final Design CR
Engineering Design CR Fabrication, Installation
Testing.
IEE, IPP, IMP with GSI
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Collector Ring superconducting magnet Magnetic
field calculation with 2 D OPERA2D 3D ANSYS
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Main parameters of the CR dipole magnet

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Cross section of the CR dipole magnet for warm
and cold pole, with separated and connected pole
and yoke
Version -1
Version -2
Version -4
Version -3
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Main design parameters for four versions
Main parameters Version 1 Version 2 Version 3 Version 4
Total width of Magnet (m) 2.25 2.20 2.04 2.21
height of the yoke (m) 1.34 1.34 1.24 1.22
width of the pole (m) 0.98 0.98 0.84 0.86
height of pole (m) 0.85 0.85 0.85 0.85
air gap between yoke and pole (mm) 25 32 40-47 No No
available width of gap (mm) 140 140 140 140
coil cross section (mm2) 5045 5050 4560 4560
maximum current density ( A/mm2) 69 A/mm2 69 A/mm2 50 A/mm2 50 A/mm2
Available area for beam line (mm2) 70 225 70 225 70 190 70 190
a 65 65 65 65
b 60 60 65 65
c 40 45 45 45
d 55 55 40 30
Cool structure for yoke and pole warm yoke and pole warm yoke and cool pole warm laminated yoke and pole warm yoke laminated and pole
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Flux density distribution along the border of the
elliptical good field area-2D
?B/B
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Flux density distribution 3D
Double arc
Trapezoidal-shaped coil
D-shaped coil
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Comparison with coil structure and further job

• ? It needs optimize slot size and placement in
  CR with 3D, three dimensional magnetic field
  calculations to check the saturation region,
  closer look at end design with superferric
  magnets, closer look at effects of allowed error
  terms in influence on the field quality, study
  lamination fabrication of coil-shaped.
• Based on OPER3D-magnetic field analysis
• ?Therefore, from view of field distribution, the
  double-arc coil is the best field quality, the
  next is D-shaped coils. The trapezoidal-shaped
  coil is the worst. From the view of manufacture
  process, the D shaped coils and trapezoidal coil
  seems are easily to be fabricated. The double-arc
  coil with the weight of superconducting wire and
  size of magnet is the smallest.
• ? Take the cold pole as former of superconducting
  coils.

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Superconducting coils for CR
Selection of wire and cable
Magnetic field in superconducting coils
Lorentz force and Mechanical stress
Quench Detection and protection
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Design of Conductor Benchmark

• ? This leads to the design choice of a
  superferric magnet with warm iron with the
  minimum cold mass option, it remarkably reduces
  the cool down time for superconducting magnet
  system and potted with epoxy resin in the wetting
  winding technique or vacuum-impregnated
  technology,
• ? The conductor with low operating current, type
  150-300 A, wound with high Cu/SC ratio
  superconducting monolith NbTi/Cu wire.
• ? For large-scale superconducting coils, the
  design of superconducting coils should be
  cryogenic stability, with large margin and lower
  hot-spot temperature and voltage during quench.

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Magnetic field distribution in superconducting
cross-sectional (a) and coils (b)-version4
Bmax 1.15 T, 2D can not obtain the maximun
field in end
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Magnetic field distribution in superconducting
cross-sectional area-3D-Trapezoid-shaped version3
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B in D-shaped superconducting coils
Bmax1.425 T
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B in Double arc-shaped coils
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Max. Operating Field of 2 T
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Cryogenic stability conductorGood Choice for
large-scale SC magnet

• ? Cryogenic stable conductors cooled by pool
  boiling helium are advantageous for high field
  magnets in a large diameter operating in the high
  current density with a modest ramp rate.
• ? The method is with high reliability, simple
  cooling arrangements and low cost at the expense
  of low current density in the winding.
• ? The cryogenic stable methods imply that any
  normal zone should recover after any disturbance.
• ? If we select the operating temperature for
  superconducting coils of 4.2 K, NbTi/Cu
  monolithic conductor with high Cu/non copper
  ratio with 5-10 is suitable.

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Proposed NbTi/Cu monolithic conductor
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Structure for Superconducting Coils
Racetrack shape
D shape
Compensation coils
Double-straight line
Trapezoidal
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Main design parameters for the coils
Conductor of NbTi/Cu Include the insulator, 0.95-1.0 mm2.0 mm
Conductor of NbTi/Cu Bare wire of NbTi/Cu 0.85 mm 1.9 mm
Conductor of NbTi/Cu Consideration of layer insulator 200-300 ?m
Conductor of NbTi/Cu Cu/SC 9 or 10.0, RRRgt 100,
Coils cross-sectional area 45 mm 60 mm
Total turn in each coils 30 turns 36 layers
Operating current 175.0 A (70A/mm2) filling factor0.646
Center field 0.8-1.6 T
Cooled way Pool cooling with liquid helium
operating current to its critical current lt 13
Quench simulation with sub. Maximum temperature lower than 100 K
Mechanics stress Helium container to supporter
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Main suggest for the superconducting coils

• ? Decreased the cross-sectional area of Coil
• from 45 60 mm2 to 30 50 mm2,
• ? Increased the operating current for
  superconducting coils, and operating current to
  its critical current ratio Iopt/Ic 20-30 ,
• ? Used the cold pole as the superconducting coil
  former to support the Lorentz force and reduce
  the displacement in straight section.

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Superconducting magnet Quench detection and
protection circuit
Type-A
Type-B
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Position of quench origin for hot spot
temperature calculation
Different scenarios
Case I
Case II
Cross section of the winding
Quench origin
Cross section of the winding
Quench origin
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Model of normal zone propagation
Superconducting coils structure
Normal zone shaped
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Results for circuit-A
Dump Resistance (ohm) 1.0 1.5 2.0 2.5 3.0
Tmax 90.0 84.8 79.7 74.7 70.0
Edump() 31.6 44.3 55.0 63.9 71.0
Vmax 306 281 372 465 558
Results for circuit-B
Dump Resistance (ohm) 1.0 1.5 2.0 2.5 3.0
Tmax 60.5 60.4 59.9 58.9 57.4
Edump() 80.0 82.9 83.7 85.4 86.2
Vmax 186 279 372 465 557
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Cryostat for Collector Ring coils
? Configuration of Cryostat ? Cooling Way of
Superconducting magnet ? Stress analysis for
Cryostat
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Design parameters for CR magnet

• 85 mm - 70 mm 15 mm
• Cryostat space is limitation
• width_1 590 mm-530 mm 60 mm
• width_2 470-420 mm 50 mm
• height_1 180 mm - 135 mm 45 mm
• height_2 90mm
• coil size
• width (530mm-470 mm)
• 60 mm
• height (170mm-110mm)
• 45 mm

coil size width (530mm-470 mm)
60 mm height (170mm-110mm)
45 mm

• Cryostat space is limitation
• width_1 590 mm-530 mm 60 mm
• width_2 470-420 mm 50 mm
• height_1 180 mm - 135 mm 45 mm
• height_2 110mm

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Scope of the cryostat design and production effort

• Vacuum vessel, external supports, and compact
  structure.
• Thermal radiation shields and intermediate
  temperature intercepts with LN2 heat exchanger.
• Multi-layer super-insulation system for thermal
  radiation.
• Suspension and anchor systems with G10.
• Cryogenic piping for cooling system.
• Cold mass end domes
• Detailed stress analysis for helium vessel and
  coils.
• Interconnecting bellows, shield bridges, and
  vacuum relief devices.

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Cool way for the CR-Superconducting magnet

• ?Pool cooling way for the coils
• ?Insulation vacuum, thermal shields, ?HTSC
  Current lead etc.
• ?No LN2 vessel needed, instead of heat exchanger.
  
• ? Forced flow, He gas and LN2 for Radiation
  shield

Beam pipe
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Main structure of the cryostat

• ?The cryostat consists of D or Trapezoidal coils,
  stainless bobbin that serves as the main
  structural support and as the helium vessel about
  12-16 structural support and link from 300 K to
  4K, a nitrogen shield and a vacuum vessel.
• ?The satellite cryostat provides all the
  connections between the superconducting coils and
  outside world including cryogenic supply, return
  and storage, pressure relief instrumentation and
  current leads.
• ?Using thermal exchanged structure to force flow
  LN2 to cool down the thermal radiation shield to
  reduce the space.
• Cooled helium gas can be used to cool the vacuum
  tube.

Cryostat consist of two main sub-assemblies 1)A
magnet cryostat housing the superconducting
coil 2)Satellite cryostat with cryogenic
reservoirs 3)Connections to outside world
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Liquid Helium vessel system

• ?LHe vessel is satellite cryostat and LHe vessel
  with contain coil ,
• ?LHe vessel should be designed according to the
  strength, stiffness and stability.
• ?A stiffening plate with rectangular hole will be
  placed LHe vessel ,
• ?The outer surface of helium vessel will be
  wrapped with 15-20 multi-layered
  super-insulation,
• ? Used for the outer supporter for
  superconducting coils
• ? Adjustment of the position and direction for
  coils.

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Calculated heat loads of LHe and Thermal shield

• To LHe
  vessel(4.2K) to Thermal shield(80K)
• heat conduction
• vertical support 66.4mW
  644mW
• horizontal adjuster 48.5mW
  351mW
• radiation 532mW
  16.61W
• Heat conduction
• of LHe neck tube 37.98 mW
  1.28W
• total 682.18mW
  18.88
• boif-off rate 0.96l/hr
  0.419l/hr

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FEM ANYLYSIS FOR main component parts

• internal pressure to outer shell of LHe
  vessel(5atm)

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Assembly processing for CR coils and yoke
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Stress analysis in Cryostat and superconducting
coils
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Survey material properties for 316,304L and the
other structure material
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Structural Design Criteria

• Static Stress Limits of Metallic Materials

• Design Tresca stress values (Sm)
• Sm Minimum values of 2/3 Sy 1/2 Su
• where, Sy is 0.2 offset yield stress Su is
  ultimate strength
• Stress allowable limits
• ? Primary membrane stress Pm ? 1.0 K Sm
• ? Primary membrane bending stress PmPb ? 1.3 K
  Sm
• Primary secondary stress PmPbQ ? 1.5 K Sm
• where, K depends on operating condition, plate
  thickness, and welding
• Fracture toughness limits
• ? Normal operation Km ? 0.67 KIC
• ? Anticipated upset operation Km ? 0.83 KIC
• ? Faulted operation Km ? 0.91 KIC

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Structural Design Criteria

• Stress Limits of Non-Metallic Materials

• Insulation materials of SC coils
• Turn insulation Kapton S-glass VPI
• Ground wrap insulation S-glass VPI
• Shear stress allowable
• S 0.5 ?0 C2 Sc(n)
• Where, ?0 pure shear bonding strength
• - In KSTAR, design value of
  ?0 is 50 MPa for fatigue cycles.
• - As a case study, the lower value of 30 MPa
  has will be used.
• C2 Slope of shear and compressive strength
• Sc(n) Applied compressive
  stress
• ?0, C2 Experimental data
• Normal tensile stress allowable
• Sn ? 1 MPa

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Structural Design Criteria

• Fatigue Evaluation of Metallic Materials

• Two approach on fatigue evaluation
• Stress-life curve evaluation No defect
  assumption
• Crack growth assessment based on linear
  elastic fracture mechanics
• Stress-life (S-N) curve evaluation
• Mean stress effect
• Cumulative damage (Miners rule) ? Variable
  amplitude cyclic stress
• Fatigue crack growth (da/dN) assessment
• Initial crack type
• ? Semi-elliptical surface crack
• ? Elliptical embedded crack
• Mean stress effect Modified Paris equation
• Safety factor(SF) Design fatigue life (2?) ?
  100,000 cycles

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Main stress analysis of Trapezoid-shaped coils
used model amd mesh
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Main stress analysis of Trapezoid-shaped coils
Used 10 mm thickness of helium vessel
Maximum Von-Misses Stress 61.3MPa, Displacement
5.98 mm
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Displacement of coils in X,Y and Z
1.449mm
3.956 mm
0.311mm
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Stress of coils in X,Y and Z
20.0MPa
48.3MPa
39.3MPa
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Strain of coil in X,Y and Z
0.1005
0.2338
0.1828
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D-Shaped superconducting 3D model
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Cryostat for SuperFRS magnet system Main
structure of the cryostat
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Main structure of the cryostat
cryostat
yoke
Pole tips
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Superconducting dipole coils for SuperFRS
Thermal shield system
Liquid Helium cryostat for SFRS system
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Comparison of Cryogenic Sensor for CR
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Conclusions

• ? Based on OPER3D-magnetic field analysis,
  optimize slot size and placement in CR with 3D,
• ?Take the cold pole as former of superconducting
  coils.
• ? Decreased the cross-sectional area of Coil,
  Increased the operating current.
• ? Detailed mechanical and thermal stress analysis
  for superconducting coils and helium vessel to
  check the outer support and thickness of wall.
  Cryostat design and analysis
• ? Subdivision protection is suitable for the
  Single magnet.
• ? Instrument interface.
• ? Superconducting coils operating and
  fabricating technology.
• ? R D experiment and test should be executed.