1. EuroCirCol: 16T dipole based on common coils (DRAFT)
T. Martinez, J. Munilla, F. Toral - CIEMAT
FCC Week, April 13th, 2016

2. Outline
Introduction
2-D magnetic design
2-D mechanical design 2

3. Introduction (I) The common coil layout is based on two flat coils.
A unique support structure for two apertures, placed at the same vertical plane.
Main advantage: pure flat coils.
Disadvantages: large stored energy and electromagnetic forces, assembly.
Traditionally, American labs (BNL, LBNL, Fermilab) have worked on this layout, even for high fields.
Chinese colleagues (IHEP) are working on a 20-Tesla dipole design based on common coils.
In the framework of EuroCirCol project, CIEMAT is working on a 16-Tesla dipole design based on common coils.
Courtesy R. Gupta (BNL) 3

4. Introduction (II)
The starting parameters are common for the three design options under study (cos-theta, block and common coil): 4

5. 2-D magnetic design
The influence of a number of parameters has been analyzed to optimize the 2-D magnetic design and to better understand the sensitivity factors:
Intra-beam distance.
Iron outer diameter.
Nominal current.
Cable: number of strands, strand diameter.
Number of coils.
Magnet protection. 5

6. 2-D magnetic design: intra-beam distance
A short intra-beam distance implies a strong cross-talk between apertures:
The superconductor efficiency decreases.
The field quality is very difficult to achieve. 6

7. Outline
Introduction
2-D magnetic design
2-D mechanical design 7

8. Overview 8

9. General remarks Magnetic forces calculation: Ansoft Maxwell
Imported to structural Ansys Mechanical
Wires modelled in Ansoft
“Coil” material for each stack of wires on Ansys 9

10. General remarks
Mechanical feasibility of a Common Coil design has been analyzed.
Internal grading version of the magnet is considered the baseline option
Mechanical properties for materials from previous agreements.
Stress limit (MPa)
293/4 K
E (GPa) P
α (293 to 4.2 K)
Coil
150
200
Ex=52
Ey=44
Gxy=21
0,3
X=3,1e-3
Y=3,4e-3
316LN
350
1050
193
210
0,28
2,8e-3
7075
480
690 70 79
4,2e-3
Iron
180
720
213
224
2,0e-3
Titanium
800
1650
130
1,7e-3 10

11. Coils Coils are modeled according two different assumptions:
Whole Package made of mean coil material
Coil blocks made of Coil material
All coils are bonded together
Coils are just supported by frictionless supports
Supports include keys for horizontal and vertical preload
Aluminum shrinkage is around iron
Loaded cases:
Assembly
Cool down (4,2 K)
Magnet ON – 16 T
Magnet ON – 18 T 11

12. Iron and Shell Different Iron configurations are being studied:
Split in vertical or horizontal axis
Alternative arrangement of iron (vertical/horizontal)
Aluminum shrinkage (cylindrical) is included, value of initial clearance is under evaluation
Values of preload and clearance of V & H keys under study
Improved stiffness is being studied by different possibilities, including for example by two-halves SS cylinder 12

13. First Results Horiz. Stress Vert. Stress Good news:
Coils stresses: < 200 T
(Sligthly
Main challenges:
Big displacements in the coils
Iron stresses
Results considering symmetry in x edge for iron 13

14. Challenges: Coils Displacement
Horiz. Displ. (mm)
Vert. Displ. (mm)
Total displacement in the order of mm in x axis
It includes small rotation of coils
Not enough lateral stiffness from iron and shell to withstand magnetic forces
Several approaches are being studied to reduce this effect
Shell deformation (enlarged) 14
Results considering symmetry in x edge for iron

15. Challenges: Iron Iron (Von Misses): 16T @ 4,2K Von Mises = 736 Mpa
Max. Prin. Stress = 232
Results considering symmetry in x edge for iron 15

16. Conclusions 2D Mechanical model for Common Coil is being studied
(Internal grading) is included
Mechanical design seems to be feasible for this kind of magnet, but more work is needed
Assembly tolerances are being included
The coil is considered completely bonded
Contacts between coil and supports are frictionless
Effect of manufacturing processes on contacts, gaps, not included
Axial support for 3D structure is not considered yet 16