Embed Size (px)
Citation preview
Single Aperture Orbit Corrector:
Progress on MCBXFB design
WP3 Meeting
J. García, F. Toral (CIEMAT)
P. Fessia (CERN)
January, 26th 2015
Requirements & specifications. Latest design presented. Mechanical analysis of the iron ring magnetic
design. New magnetic optimization. Conclusions & decisions to be made. Next steps.
Index
2
Requirements & specifications
3
MCBXFB Requirements
4
Magnet configuration Combined dipole (Operation in X-Y square)
Minimum free aperture 150 mm
Integrated field 2.5 Tm
Baseline field for each dipole 2.1 T
Magnetic length 1.2 m
Physical length 1.505 m
Working temperature 1.9 K
Nominal current < 2500 A
Field quality < 10 units (1e-4) *
Fringe field 40 mT *
Iron geometry MQXF iron holes
Strand parameters
Cu:Sc 1.75Strand diameter 0.48 mm
Metal section 0.181 mm2
Nº of filaments 2300Filament diam. 6.0 µm
I(5T,4.2K) 200-210 AJc 2800-3300 A/mm2
Cable parameters
No of strands 18Metal area 3.257 mm2
Cable thickness 0.845 mmCable width 4.370 mmCable area 3.692 mm2
Metal fraction 0.882Key-stone angle 0.67 degInner Thickness 0.819 mm
Outer Thickness
0.870 mm
Strand & cable specificationsInsulation: Fibre glass sleeve• This method provides stiffer coils for an
easier double layer winding.• Need validation test of a suitable binder:
• Ceramic binder is not applicable (only in cured state).
• Some PVA studies are ongoing but compatibility with impregnation has to be demonstrated.
• Ceramic binder substitute (suggestion by CTD) is being tested by CERN.
*To be discussed at this meeting
Latest design presented(November 2014)
5
6
Two main problems:
Saturation at nominal current for both dipoles causes the increasing of sextupoles:◦ ∆b3= 37 units◦ ∆a3= -25 units.
Large radial deformations (causing possible poor training).
Two solutions proposed:
New magnetic design using an iron ring placed further away.
Larger collars in order to increase the stiffness of the assembly and make them self-supporting.
Worst case:IID & IOD variation from 10% to 100%
7
Current increase from previous design: IID=1885 A (prev. 1560 A) IOD=1870 A (prev. 1340 A) Greater forces!Saturation multipoles: b3= 17 (prev. 37) a3= 18 (prev. 24)
New magnetic design
Ansyssimulationusing the
new forces(108% IN)
Worst case:IID=100% IOD= Var. from 10% to100%
Mechanical analysis of theiron ring magnetic design
8
9
Any of the actions taken to increase the stiffness of the assembly decreased the radial displacements of the outer coils.
Ellipticity
10
However, the action of an external shell or increasing the outer collars thickness do not reach the inner coils, given the assembly gap between inner collars and outer coils.
GAP
GAP
Outerpressure
Magnetic forces (Both dipoles at
108% IN)
The only way to decrease the inner dipole ellipticity is to increase inner collars thickness.
11
New geometry
OD Max Ellipticity= 0.3175 mm(prev 0.3485 mm)ID Max Ellipticity= 0.3064 mm(prev 0.4828 mm)
Geometrical changes:• Inner collar thickness increased
in 6 mm (21 mm -> 27 mm).• Outer collar thickness increased
in 2 mm (31 mm -> 33 mm).• Outer dipole aperture increased
from 218 mm to 230 mm.• Outer collar diameter increased
from 300 mm to 316 mm.
• It is difficult to put a limit on the radial displacements. • The main goal has been to make it as stiff as
possible while keeping reasonable dimensions.• It has to be highlighted also that each mm of
additional steel has less effect than the previous one.
12
Mechanical analysis: Contact between coils and collars
1
2
21
1 2
13
Mechanical analysis: Coil stress
Assembly Cooldown Load
All these results were obtained using the inner Titanium tube.Possible re-evaluation considered.
100% IN
Low radial tension at spacers edges, caused by friction
Low azimuthal tension caused
by friction
New magnetic optimization
14
Inner coil (ID) & Outer Coil (OD) parameters
Units Whole iron Iron ring Only cryostat
Nominal field 100% (ID) T 2.11 2.11 2.11
Nominal field 100% (OD) T 2.11 2.11 2.11
Nominal Field (Modulus, 100% ID & 100% OD) T 2.99 2.99 2.99
Nominal current (ID) A 1590 1870 1950
Nominal current (OD) A 1390 1895 2070
Coil peak field (Modulus, 100% ID & 100% OD) T 3.94 (ID) 4.18 (ID) 4.25 (ID)
Working point (Modulus, 100% ID & 100% OD) % 48.49 53.39 54.8
Max fringe field, 20 mm out of the cryostat (Modulus, 100% ID + 100% OD)
mT 29 100 165
Sextupoles variation ∆b3 / ∆a3 (Worst case) units 37 / -21 15 / 14 2 / 5
Iron yoke Inner Diam. mm 316 432 -
Iron yoke Outer Diam. mm 610 610 -
Torque 105 Nm/m 1.2 1.42 1.48
Mean stress at the coil and collar nose interface
MPa 84 98 102
15
Using the new geometry:• Outer dipole aperture = 230 mm.
• Collars outer diameter = 316 mm.
16
Sextupoles monitoring
17
Field quality optimization difficulties
o Other iron geometries were tested, with similar or worse field quality results:
o The difficulty comes because the field changes in two ways depending on the powering scenario: Orientation and intensity.
o One of these variations could be assumed optimizing the iron geometry.
o Both of them combined make any optimized geometry useless when the powering scenario changes, because symmetry conditions are lost.
18
Fringe field and iron screening effectiveness
o It is not possible to screen the field below 40 mT without the whole iron, a lot of magnetic material would be necessary.
o Adding a warm screen and measuring the fringe field 20 mm from its surface:• Rin= 467 mm, Thickness = 10mm, Max Fringe field = 131 mT.• Rin= 467 mm, Thickness = 50mm, Max Fringe field = 31 mT.
o Other magnetic materials like mumetal would not be a solution, since they have higher permeability, but lower saturation field.
o The main problem is that we deal with a dipole: the dipole field decays as 1/r2
compared to quadrupole field which decays as 1/r3.
o Therefore, we should choose between:• Higher fringe field or• Higher variation of the multipoles with the current (when magnetic
materials shield the dipole field).
19
Coil ends: First results (without iron)
o Field quality achieved but peak field still high. o Several approaches being evaluated. Currently
checking how splitting blocks could help.o Coil ends length 200 mm.≅o Coils length 1400 mm.≅o Total magnet length = 1505 mm (Current layout).
Conclusions & decisions to be made
20
Conclusions
21
Mechanical design:◦ Whichever the mechanical design used, the radial
displacements in the inner dipole can only be contained using the inner collar.
◦ The thickness of the inner collar will depend on the current in the inner coil and the radial displacement allowed for the inner coil.
Magnetic design:◦ It is not achievable to meet both fringe field and field
quality requirements simultaneously.
Decisions to be made
22
Inner & Outer dipole apertures.
Iron geometry (if any).
Next steps
23
February ‘15: 3D Magnetic Optimization
March ’15: Winding Machine.
April ‘15: Short mechanical model.
October ‘15: First coil.
CERN: Binder tests.
Thanks for your attention
24
Annexes
25
Mechanical design: Challenges to face
26
As a combined dipole that requires a square range of operation in X and Y axis, a large torque arises when both coils are powered.
Due to the expected radiation dose a solution based on mechanical clamping is required to mechanically fix the coils and guarantee the magnet performance.
Other major challenges:
Mechanical model◦ Powered with 108% of nominal current for sizing purposes.◦ Material properties used:
Material E [Gpa] u [-] CTE [K-1]
Coils & spacers (Impregnated) NbTi+Cu 40 0,0032 1.1*10-5
Collars StainlessSteel 193293K/2104.3K 0,0028 0.983*10-5
Inner tube Ti 130 0,0017 0.603*10-5
Radial inward forces at the inner dipole Inner titanium tube
Large azimuthal displacements of the coils Azimuthal interference at collar noses
Large radial deformations of the assembly Large self-supporting collars
Challenge Solution proposed
Considerations on a MCBXFB design based on a canted cosine-theta coil configuration
27
Comparing the main challenges in the case of MCBXFB design for both designs:◦ The torque between nested dipoles:
It will be the same for both designs.◦ The separation of the pole turn from the collar nose due to the Lorentz forces:
It does not happen in the CCT dipole (azimuthal forces support). In the pure cosine-theta it can be overcome with a small interference between the collar
nose and the pole turn of the coil.◦ The elliptical deformation of the support structure under Lorentz forces:
In a CCT dipole the outer formers should hold the outwards radial forces coming from the inner layers, which complicates significantly the assembly and fabrication.
The assembly of two nested collared coils is not easy, but seems more affordable.
The CCT configuration has not been broadly used up to now, so other open questions are:◦ The handling of the axial repulsive forces between layers.◦ The influence of the cable positioning accuracy on the field quality.◦ The training of a large and high field superconducting dipole.◦ The protection of the magnet in case of quench.◦ Formers materials to be used (insulation, stiffness and easily machining required).◦ Coils impregnation.
Some useful expressions to understand where mechanical stresses come from
28
𝐼𝑇=∫− 𝜋2
𝜋2
𝐽 dl=∫− 𝜋2
𝜋2
𝐽 0 cos𝜃𝑅 dθ=2 𝐽 0𝑅 𝐽 0=𝐼 𝐼𝐶2𝑅
𝑇𝑙= �⃗�× �⃗�
𝑙=𝐵𝑂𝐶
𝑙 ∫− 𝜋2
𝜋2
𝑆 ∙ 𝐼=𝐵𝑂𝐶 ∫−𝜋2
𝜋2
2𝑅𝐼𝐶 cos𝜃 𝐽 0 cos𝜃 𝑅𝐼𝐶dθ
dl
Rθ
d=2Rcosθ
IIC-IIC
BOC
J[A/m]=J0cosθ
�⃗�
𝑻𝒍
=𝝅𝟐𝑹𝑰𝑪𝑩𝑶 𝑪 𝑰 𝑰𝑪
T
R
R
h F
F
𝝈𝜽𝒄𝒐𝒏𝒅=𝑭𝑨
=𝑻 /𝟐𝑹𝒍𝒉
=𝑻 /𝒍𝟐𝑹𝒉
𝑻𝒍
=𝝁𝟎𝝅𝟖
𝑰 𝑰𝑪 𝑰𝑶𝑪
𝑹𝑰𝑪
𝑹𝑶 𝑪 (𝑹𝒀𝟐+𝑹𝑶𝑪
𝟐
𝑹𝒀𝟐 )*
* Linear Iron
29
Model settings and convergence challenges
2D Ansys Workbench model. 0.5-mm-thick shell elements at the collars. 1-mm-thick shell elements for the rest of the assembly.
Load steps. t=0-1: Contact offset (pre-stress). t=1-2: Assembly cooldown. t=2-3: EM forces (exported from Maxwell, 108% Nominal current).
Convergence/stability challenges No symmetry boundary conditions can be used. DOF more
difficult to constrain. Many parts involved and linked by contact. Frictional contacts
showed better performance that frictionless ones. Techniques used to achieve convergence:
Adding extra boundary conditions. Tuning up contact settings at problematic zones (Stabilization
dumping factor, Normal stiffness, ramped effects...).
Materials
30
Cable, wedges and inter-layer insulation: glass fibre sleeve impregnated with binder treatment as hardener (PVA to be studied).
Wedges: machined from ETP copper. End spacers: 3D printed in stainless steel. Ground insulation: Polyimide sheets Vacuum impregnated coils, radiation hard resin (cyanate-ester
blend). Collars: Machined by EDM in stainless steel. Iron: To be evaluated. Connection plate: Hard radiation resistant composite, like Ultem. End plates: Stainless steel. Inner pipe: Titanium grade 2 if grade 5 is not available.
Winding
31
Customized winding machine lent by CERN◦ New beam: 2.5 m long.◦ Electromagnetic brake.◦ Horizontal spool axis.
Winding process◦ Stainless steel mandrel protected with a polyimide sheet.◦ Binder impregnation and curation.◦ Outer layer will be wound on top of the inner one with an
intermediate glassfiber sheet for extra protection.◦ Vacuum impregnation with hard radiation resin.
Assembly
32
Collars placed around the coils with a vertical press (custom tooling required).
Layer of protection between both dipoles, likely a glass fibre sheet
Innermost turn of the coils will be protected by a stainless steel sheet from the collar nose sliding.
Iron laminations around the coil assembly.
Protection
33
CIEMAT in-house developed codebased on finite difference method :Optimistic assumptions of the model
34
Rutherford cable is modeled as a monolithic wire with the same metallic area, discarding the voids or internal volumes filled with resin.
The wedges are not modeled. Quench origin is placed at the innermost turn,
although it is not where the peak field is placed when both coils are powered.
A uniform magnetic field is assumed in the wires, equal to the peak field.
MCBXFB: No damping resistance included
35
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
200
400
600
800
1000
1200
1400
1600Current decay in quench
Cu
rren
t (A
)
Time (s)0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
0
20
40
60
80
100
120
140
160
180
200Maximum temperature in quench
Tem
per
atu
re (
K)
Time (s)
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4Coil resistance in quench
Res
ista
nce
(O
hm
)
Time (s)0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
0
50
100
150
200
250Quenching coil voltage
Vo
ltag
e (V
)
Time (s)
Preliminary
MCBXFB: Damping resistance = 0.3 Ω (0.1 s delay)
36
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.90
200
400
600
800
1000
1200
1400
1600Current decay in quench
Cu
rren
t (A
)
Time (s)0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
10
20
30
40
50
60
70
80
90Maximum temperature in quench
Tem
per
atu
re (
K)
Time (s)
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.90
0.01
0.02
0.03
0.04
0.05
0.06Coil resistance in quench
Res
ista
nce
(O
hm
)
Time (s)0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
0
5
10
15
20
25
30
35Quenching coil voltage
Vo
ltag
e (V
)
Time (s)
Preliminary
No quench heaters seem to be necessary
MCBXFA: No damping resistance included
37
0 0.2 0.4 0.6 0.8 1 1.2 1.40
200
400
600
800
1000
1200
1400
1600Current decay in quench
Cu
rren
t (A
)
Time (s)0 0.2 0.4 0.6 0.8 1 1.2 1.4
0
50
100
150
200
250Maximum temperature in quench
Tem
per
atu
re (
K)
Time (s)
0 0.2 0.4 0.6 0.8 1 1.2 1.40
0.1
0.2
0.3
0.4
0.5
0.6
0.7Coil resistance in quench
Res
ista
nce
(O
hm
)
Time (s)0 0.2 0.4 0.6 0.8 1 1.2 1.4
0
50
100
150
200
250
300
350
400
450Quenching coil voltage
Vo
ltag
e (V
)
Time (s)
Preliminary
MCBXFA: Damping resistance = 0.3 Ω (0.1 s delay)
38
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.90
200
400
600
800
1000
1200
1400
1600Current decay in quench
Cu
rren
t (A
)
Time (s)0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
10
20
30
40
50
60
70
80
90Maximum temperature in quench
Tem
per
atu
re (
K)
Time (s)
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.90
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0.045Coil resistance in quench
Res
ista
nce
(O
hm
)
Time (s)0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
0
5
10
15
20
25Quenching coil voltage
Vo
ltag
e (V
)
Time (s)
Preliminary
