jt-60 sa toroidal field coil structural analysis
TRANSCRIPT
Ch. Portafaix 07 April 2009JT-60SA TF magnet structural analyses
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JT-60 SA Toroidal Field coil structural analysis
Christophe Portafaix
• Introduction
• TF coil description
• TF coil design and electromagnetic loads
• Material and Criteria
• 2D structural analysis
• 3D structural analysis
• Conclusion
Ch. Portafaix 07 April 2009JT-60SA TF magnet structural analyses
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Vacuum vessel
Central Solenoid (CS)
Cryostat
Toroidal Field (TF)
coils
Equilibrium Field (EF) coils
~14m
Nominal parameters
Plasma major radius = 2.95 m
Plasma minor radius = 1.18 m
Aspect ratio = 2.5
Plasma current = 5.5 MA
Toroïdal magnetic Field = 2.26 T
Introduction
JT-60SA
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case
Gravitysupport
18 TF coils
TF coil description Inner leg section
Conductor NbTi6 Double pancakes Temperature 4.4 KCurrent 25.7 kAHe flow rate 4 g/sPeak field 5.65 TTmargin > 1 K
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TubeTubeInner Inner øø 90mm90mm
Outer Outer øø 140mm140mm
1.5m1.5m
1.4m1.4m
Gravity support
Spherical Joints:Spherical Joints:
Permit to reduce transmitted Permit to reduce transmitted loads (no moment).loads (no moment).
Tube section optimized to Tube section optimized to reduce heat leak.reduce heat leak.
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Radial net force= 23MN
Wedging of the TF Coils to withstand ‘Centring’ Loads
TF coil design and electromagnetic loads
Wedged
HoopCompression
TF
Coil Contact Areaon Sides
CS
In plane load
Fr and Fz : I ^ Bφ
r
z
Forces caused by TF current and toroidal field
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T=(1/2) IBρBm=µ0NI/(2πr1)
r1 minimum distance from z axisT=I ρ Bmr1/(2r)
To maintain T constant and no bending moment:ρ=kr with k = 4 πT/(µ0NI2)In plane (z,r), the curve must satisfy the following equation:
[ ] 2/32
2
2
)(11drdz
kdrzd
r +±=
Toroids Forces Winding with constant tension Discussion on thin shell
r
z
Segment of the windingwith local curvature ρ
In plane load Fr and Fz : I ^ Βφ
Bending free : D shape
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Fz =5 MN
Fr= I* <Bphi> =5. MN/m (I=72*25.7kA <Bphi>=5.6/2T )
Fphi=Fr/(2 * sin 10 °) =14.4 MN/m
The centring force is supported by a vault effect in the TF nose (Fphi)
In plane load Fr and Fz : I ^ BφφφφInner leg section
F r
Fz Fphi
• Inner leg wedged
z
r
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Case: Stainless steel
Inner leg section
Eddy current insulation: glass epoxy
Jacket: Stainless steel
Insulation : glass epoxy
cable
Case cooling channel : stainless steel
Stainless steel: 51% of the inner leg section
NbTi: 4.5% of the inner leg section
SS to withstand Lorentz forces
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Connection of the TF Coils to withstand out of plane loads
N 11 GR 294 97-12-03 W 0.2
IM
NUL
EOB
SOB
SOF
XPF
Out of plane loads Fφφφφ : I ^ Br and Bz
Forces caused by TF current and poloidal field
Structural links have to include an eddy current insulation
Cyclic loads fatigue
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Out of plane loads Fφ φ φ φ : I ^ Br and Bz
• OIS, bolts, keys withstand the Out of plane loads
• Friction between inner leg play an important role in supporting the out of plane loads
OIS
case
z
r
keys
bolts
OIS is separated from the coil casing:
• Simplify the manufacturing
Reduced welding in the coil casing
• Simplify cold testing
• Reduce hoop forces in the bolted connections, thus reducing number of bolt
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Mechanical properties at 4K
0.3%0.5%0.7%0.3%Thermal contraction dl3/l
0.3%0.5%0.25%0.3%Thermal contraction dl2/l
0.3%0.5%0.25%0.3%Thermal contraction dl1/l
0.384679Coulomb’s Modulus G13 (GPa)
0.384679Coulomb’s Modulus G23 (GPa)
0.384679Coulomb’s Modulus G12 (GPa)
0.30.30.330.3Poisson’s ratio nu13
0.30.30.330.3Poisson’s ratio nu23
0.30.30.170.3Poisson’s ratio nu12
1712205Young’s modulus E3 (GPa)
1720205Young’s modulus E2 (GPa)
1720205Young’s modulus E1 (GPa)
cableResinInsulationEpoxy glass
Stainless steel
1 and 2 along layer direction, 3 perpendicular to layer direction
Material and Criteria
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Stainless steel criteria
Limit stress value: Sm= 547MPa : 2/3 of the yield strength at 4K (820MPa)
• Membrane stress Pm < K*Sm
• Membrane + bending stress < 1.3*K*Sm
Base metal : K=1
Welds : K=1 for plates under 20mm thick
K=0.9 for plates from 20 to 150mm
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Insulation criteria(σn/σ0)+(τn/τ0)
2 < 1 (LHD criteria [1])
σ0: tensile strength at 77K= 38Mpa τ0: shear strength at 77K= 27Mpa
σn: stress perpendicular to the glass fiber
τ n: shear stress
Compressive strength:
600 MPa
[1] Cryogenic shear fracture tests of interlaminar organic insulation for a forced-flow superconducting coil, MT13, Victoria BC, Canada 1993, K. Kitamura et al., NIFS.
-80
-60
-40
-20
0
20
40
60
80
-80 -60 -40 -20 0 20 40
Sig NN (MPa)
Tau
NS
(M
Pa)
ITER criteria static
LHD criteria static
ITER criteria fatigue
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• The calculations are performed in 2D generalised plane strain hypothesis: constant vertical strain corresponding to a verticalforce Fz
Load steps:
1. Cool down from 293K to 4K 2. Cool down + In plane Lorentz forces3. Cool down + In plane Lorentz forces + pressure (quench)
2D structural analysis
Inner leg section
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Magnetic field map in the JT60-SA TF winding pack (T)
Bmax =5.6T
Fr=5. MN/m
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Von Mises Stress map in conductor jacket (MPa).
Maximum von Mises stress = 494MPaRadial displacement (m).
Maximum contact gap distance = 1mm
Load: Cool down + In plane load
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In plane loadNormal stress along the wedge contact.
σn max = 351MPa (compression stress) < 600 MPa Glass epoxy. (limit)
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Cool down + In plane load
Von Mises Stress intensity map in casing.
Maximum Von Misesstress = 447MPa.
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Load: Cool down + In plane load
12
00
=
+
ττ
σσ nn
The LHD criterion for insulation.
σ0: tensile strength at 77K = 38MPa, τ0: shear strength at 77K = 27MPa.σn: stress perpendicular to the glass fiber,τn: shear stress
LHD criteria max = 0.636 < 1
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3D structural analyses
case
OIS
TF coil
CS1
CS2
CS3
CS4
EF3EF2
EF1
EF4 EF5
EF6
FP1
FP2
FP3
FP4
FP5
FP6
TF3
TF2
TF1
TF, CS, EF coils and Plasma
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Electro-magnetic analysis
• In plane forces calculated with TF current only (25.7kA per conductor)
S = 0m S = Smax/2
In Plane Forces (EOB)
1.8
2.3
2.8
3.3
3.8
4.3
4.8
0 2 4 6 8 10 12 14 16 18
s (m)
Mag
net
ic f
orc
e (M
N/m
)
Upper
Inner
Leg
Lower
Inner
LegTF3 TF3’
TF2 TF2’TF1
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Electro-magnetic analysis• Out of plane forces determined
S = 0m S = Smax/2
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Lateral displacementLateral displacement
@ SOF ~ 20mm@ SOF ~ 20mmLocal peak stressLocal peak stress
@ shear panel connection@ shear panel connection
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Max stressMax stress < 140 < 140 MPaMPaBending stressBending stress < 10 < 10 MPaMPa
Load: Weight + Seism
Max stress <130 Max stress <130 MPaMPaBending stress < 20 Bending stress < 20 MPaMPa
Load: Weight + VDE
Gravity support
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Conclusions
• TFC structures design is well advanced.
• Design optimized in order to reduce mass and cost
• Actually detail design tasks are ongoing.
• Future activities (local models, half torus model) are planned.