1. the MDP High Field Dipole Demonstrator
Design and Status of
the MDP High Field Dipole Demonstrator
FCC Week in Berlin, May 29-June 2, 2017
Alexander Zlobin
US Magnet Development Program
Fermi National Accelerator Laboratory

2. Outline Magnet design and parameters Magnetic and mechanical analysis
Magnet fabrication status
Conclusion

3. Cos-theta 15 T Dipole Demonstrator: design selection
Approach:
use the available tooling and FNAL fabrication and test infrastructure to reduce the magnet R&D cost and time
Coil:
60-mm aperture
4-layer graded cos-theta coil
5 cross-sections studied
Mechanical structure:
Design 1: SS C-clamps and 20-mm thick SS skin
Design 2: Al I-clamps and 12-mm thick SS skin
Design 3: 50-mm thick Al shell

4. MDP High Field Dipole Demonstrator design
Coil:
60-mm aperture
4-layer graded coil
Wsc = 68 kg/m/aperture
Cable:
L1-L2: 28 strands, 1 mm RRP150/169
L3-L4: 40 strands, 0.7 mm RRP108/127
SS core
Insulation: E-glass tape
Mechanical structure:
Thin StSt coil-yoke spacer
Vertically split iron laminations
Aluminum I-clamps
12-mm thick StSt skin
thick end plates and StSt rods
Cold mass OD<610 mm (VMTF Dewar limit)

5. Magnet Parameters
T=1.9 K
100% SSL
87% SSL

6. 3D magnetic analysis
50% filling factor
100% filling factor
Cylindrical cut-out
Outer block splits for structural reasons
Increased distance for magnetic reasons
Peak field is in the straight section
Coil end were optimized to take into account structural and magnetic considerations
Without the iron cutout, Bpeak in the coil end is 2% higher than in the straight section
Removing ~45 mm of the iron yoke around coil ends reduces end Bpeak to the level of the straight section Bpeak

7. Coil magnetization effect and its correction
For selected conductor parameters the peak values of b3=-48 and b5=+8 B~1.4 T.
50-75 deg
Geometrical b3=-0.8 and mm thick iron strips: 0.4mT<B3< 0.1mT at B>1.4 T
B3 range reduction by a factor of 11.
LHC MB b3~-7 units
LHC MBH b3~-25 units
3 layers of 1 mm SC wires:
-0.4mT<B3< 0mT at B>0.7 T
B3 range reduction by a factor of 13.

8. 2D mechanical analysis 300K Seqv=133 MPa 4K Seqv=176 MPa 4K+15T
Bdes=15 T
Seqv=133MPa
Seqv=182MPa
Seqv=161MPa

9. Towards 16 T dipole Magnet Bssl>17 T at 1.9K
Mechanical limit Bmax~15T
Large horizontal force and low radial coil rigidity
large horizontal coil deformation
stress concentration in L1 midplane (Bmax)
presented at IPAC2017

10. Magnet assembly steps 15 T Dipole Mechanical Design and Analysis
February 6, 2017

11. SC strand and cable Cable parameters Cable development
L1-L2: 28 strands, 1 mm RRP150/169
L3-L4: 40 strands, 0.7 mm RRP108/127
0.025 mm by 11 mm SS core
Cable development
40-strand outer-layer cable was developed for 11 T Dipole
Inner-layer cable:
Effect of cable Packing Factor on Ic degradation and RRR
Final cable cross-section parameters have been selected – PF~87%, Ic degradation <5%, RRR>100
HT optimization to achieve optimal Jc and RRR
Magnet SSL estimated based on the cable test data:
11.05 kA (Bap=15.3 T) at 4.5 K
12.2 kA (Bap=16.7 T) at 1.9 K.
Cable fabrication
420 m of 28-strand cable
350 m of 40-strand cable + leftover from the 11 T program
RRP-108/127
0.7 mm
RRP-150/169
1 mm

12. Mechanical stricture

13. Axial support structure

14. Mechanical Model MM design: iron laminations Al I-clamps
coil-yoke shim
instrumented “dummy” Al coils (short and full-size)
Goals:
Test assembly tooling and main components of the mechanical structure
Develop coil assembly plan and prestress targets
Compare experimental data with the FEA

15. Coil part design and optimization
4-layer coil, complicated 3D parts
End parts have been iteratively designed using the BEND/3D printing process
L1/2 and L3/4 practice winding completed with satisfactory results

16. Coil components L1/2 parts (CERN) Cable and L3/4 parts (FNAL)
Traces (LBNL)
Real international effort!

17. Coil fabrication status: L3/4 coil #1
Coil winding
Coil curing
Preparation to reaction

18. Summary
15 T dipole demonstrator has been developed and now is being fabricated
important MDP milestone, collaboration with LBNL
contributions from CERN - great integrated international effort
Magnet fabrication status
fabricate 4 coils – November 2017
assemble and test MM – June-November 2017
assemble the HFDD model – November 2017-January 2018
model test – February-March 2018
Magnetic and mechanical analysis
confirmed soundness of the selected design
helped to understand design limitations
The work on increasing the nominal field to 16 T with appropriate margin has started