MCBX Design

1. MCBX Design First approaches J. García, F. Toral, J. Munilla – CIEMAT

2. Index • MCBX Requirements. • Strand & Cable. • Different approaches to shorten magnet length • 18 vs 36 strands alternative Cable. • Coil ends: First Tests with 18 strands. • One vs Two layers at each coil. • Mechanical Issues • Torque analytical expression and estimated stress • First 2D FEA analysis • Manufacturing options • Open issues

3. MCBX Requirements • Combined Dipole (Operation in X-Y plane) • Aperture diameter = 150 mm • Integrated field = 2.5 Tm • Working temperature = 1.9 K • Magnetic length ≅ 1.2 m • Working Point = 65% • Field Quality = Multipolesbelow 10 units. • Desirable features: • Larger operational field (up to 3T). • Shorter coil ends

4. Strand & Cable * Extracted from strand March -09 Waiting for better estimates from Amalia 275 km SC-strand in stock at CERN Polyimide Insulation: 2 x 25µm + 55 µm (in stock at CERN)

5. Different approaches to shorten magnet length At these approaches: • Inner and Outer Coil (IC&OC) were optimized for a good field quality without iron (few units). • Iron Yoke • 4 Holes of Ø90mm at 190mm from the center • Outer diameter = 540mm

6. Different approaches to shorten magnet length • 1- A 36 strand alternative cable was considered • No optimization (same block design than in the 18 strand case was used, only for comparative analysis) • CABLE04 from Roxie repository: • Same strand. • Known geometry and properties. • 2- Coil ends: First 3-D models evaluated in order to consider the possibility of shorter coil ends. • 3– One vs Two layers for each coil: In order to increase field and additionally decrease current.

7. 1- 18 vs 36 strands comparative Currents above 2500A give bad side effects on powering, so the high currents required for the 36 strands cable case discarded this design

8. 2- Coil ends: First Tests • First 3-D models in order to consider the possibility of shorter coil ends. • Tests carried out with IIC=3000A and IOC=0 (60% Load) using previous 2D design (18-strand cable) • Straight section length ≅ 0.86 m • The goal is that peak field at coil ends would not be greater than in the straight section.

9. Warning! Mechanical behavior of the cables was not considered at this point 2- Coil ends: First Tests Interesting option? ≅130mm ≅175mm

10. 3- One vs Two layers comparative

11. 3- One vs Two layers comparative

12. Mechanical issues - Analytical torque BOC J[A/m]=J0cosθ dl d=2Rcosθ R θ -IT IT

13. Estimated stress in the conductors h F T R R F Twice the stress at old MCBX anyway!! (1 or 2 layers)

14. Approach to decrease the stressIntermediate support Stress at coil-collar interface decreases to approximately 100 MPa • However this design has important drawbacks: • A good field quality is difficult to achieve. • Difficult assembly process.

15. First 2D FEA analysis: Magnetic model • 18 Strands • Double Layer • 15 mm between coils Simplified model of a combined dipole with 60 deg sectors that provides an equivalent field in order to obtain similar stresses to those on… 2.88T ≅ 4T 2.85T

16. First 2D FEA analysis: Analytical results First of all, the analytical results were checked in order to: - Asses them as design tools. - Provide an idea of the usefulness of the complete model. Moment Reaction for all edges fixed at Inner coil: TIC=1.7686•105 Nm/m (Reasonably close to the 1.8725•105 Nm/m of the Roxie model) Force reaction=1100N (Without taking stress concentration into account) Reasonable results!

17. First 2D FEA analysis: Complete model • Only magnetic forces were considered • All contacts bonded unless those between coils and collars, Frictional with μ=0.2 • Collars: E=200GPa • Coils: E=40GPa • Support = Remote displacement in the outer edge of the collars

18. First 2D FEA analysis: Coil Results

19. First 2D FEA analysis: Collar Results

20. First 2D FEA analysis: Displacements

21. First 2D FEA analysis: Next steps • Interference studies to provide pre-compression to the coils. • Collar design to avoid stress concentrationand coil inwards movement. • Cable mechanical and thermal properties for cryogenic temperatures. • Thermal load 300K->1,9K

22. Manufacturing Options: One vs two layers • One layer: • More difficult connection. • Less conductors and easier winding • Less field with higher current. • Same stress at the coils. • Two layers: • Easier connections. • Much more conductors. • More field with lower currents. • Same stress at the coils.

23. Manufacturing Options: Insulation • Kapton: • Better cooling. • More difficult assembly. • Resin-impregnated glass fiber tape: • Easier assembly. • More difficult tooling.

24. Open issues: Iron geometry • MCBX will come with two iron flavours • MQXF Iron holes Round vs flat edges at iron file??

25. Open issues: Iron geometry • MCBX will come with two iron flavours • D1 Iron holes 190 mm (Giovanni’s slides) VS 210 mm (MBXD & MBXE iron files) 210 mm Keypointsseparated 0.0499 instead of 0.05 at iron files??

26. Open issues: Jc-Fit • More accurate Jc-Fit is going to be provided. Last estimations suggest the margin is going to decrease with these new fit, compared to FIT1 (Roxie) Roxie FIT1 Values provided by Ezio

27. Open issues: 3D coil ends • Mechanical behaviour of the 3d Coil ends • De-keystoning modelling

28. Thanks