1. Zian Zhu Magnet parameters Coil/Cryostat/Support design Magnetic field analysis Cryogenics Iron yoke structure Mechanical Integration Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu

2. Basic Parameters(1) Physics requirement Central fieldB = 1.0 T Dimension of magnet(RT volume): L = 3.89 m, D = 2.65 m Uniformity  B/B < 5% in the tracking volume Cool-down timet < 10 days Configuration Single layer solenoid coil, steady field In-direct cooling by two phase flow liquid helium Pure aluminum based stabilizer NbTi/Cu superconductor Ramp rate: reached to operating current in 0.5hours Recovery time: <1 day Field stability: 5×10 -4 Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu

3. Basic Parameters(2) Cryostat Inner radius 1.325m Outer radius1.7m Length3.89m Coil Effective radius1.45m Length3.5m Cable dimension3.7mm*20mm Electrical parameters Central field1.0T Nominal current3150A Inductance2.0H Stored energy9.2MJ Cold mass3.5ton Total Weight14.6ton Radiation thickness1.86X 0 Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu

4. Coil Design(1) 4N Purity aluminum-stabi1izer RRR=~300 Cross section of the superconducting cable 921 turns for a 3.5m long coil = 9.2MJ = 2H 20mm,w=3.7mm,I=3150A Working 3150A@1T-----Critical 6300A@2T NbTi wire ， JC=3800A/mm2@2T, NbTi/Cu ratio 1.09:1 Cross Section Area of NbTi/Cu: 3.2mm 2 3.2m m 2 Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu

5. Coil Design(2) Stress in the Coil Hoop stress Radial Magnetic Pressure t is thickness of coil plus support cylinder When thickness of support cylinder is 20mm, t=35mm Maximum hoop stress is 19 Mpa Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu

6. Coil Design(3) Other analysis Voltage versus length of quench area in the coil Coil Ohmic heat by the joints: 2.54 mW Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu

7. Coil Design(4) Coil Cross Section Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu

8. Magnetic field analysis(1) Flux line End Yoke L1~L9 30,30,30,30,30,40,80, 80,80mm Barrel Yoke L1~L9 30,30,30,40,40,80,80,80,150mm When anti-solenoid excited Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu

9. Magnetic field analysis(2) Field Uniformity in the Drift Chamber Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu

10. Magnetic field analysis(3) Fringe field analysis Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu By following methods: 1. Adopting “Cap” construction on the gap 2. Increase the thickness of barrel yoke layer9 from 8 cm to 15 cm 3. A magnetic shield near ISPB region 4. Connect the shield to pole tip magnetically can decrease the fringe field further. B along beam axis

11. Cryostat Design(1) Material: SUS316L Buckling check Outer cylinder,Inner cylinder,End plates Mechanical strength check Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu

12. Cryostat Design(2) Max. Stress: 43 MPa Max. Deformation: 0.18mm Thickness: Outer vessel =16 mm Inner vessel = 5 mm End vessel = 32 mm Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu

13. Coil Support Structure(1) 12 radial support rods 6 at each end 12 axial support rods at chimney side Rods material: GFRP Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu

14. Coil Support Structure(2) Axial decentering force416340 N/5cm Radial decentering force34695 N/5cm Diameter of the rods for the nitrogen shield is 15mm, 6mm for radial and axial support. Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu

15. Weight and Radiation thickness Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu

16. Cryogenics(1) Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu

17. Cryogenics(2) Cooling Type Normal: Forced 2-Phase Helium Cooling Trouble: Thermo-syphon Cooling Volume of Working Fluid Coil: 50 L Service Port: 200 L Shield: 16 L Coil Pipe Outer Diameter: 31 mm Inner Diameter: 25 mm Total Length: 102 m Number of Line: One Shield Pipe Outer Diameter: 18 mm Inner Diameter: 14 mm Total Length: 70 m Number of Line: Two (One for each side) Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu

18. Cryogenics(3) Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu

19. Iron Yoke(1) Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu Design outline: Occupy smallest Muon space, Less assembly time, Limit by 3.7m height from IP to ground, Field uniformity in the tracking volume, Fringe field requirement

20. Iron Yoke(2) Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu End Yoke L1~L9 30,30,30,30,30,40,80, 80,80mm Barrel Yoke L1~L9 30,30,30,40,40,80,80,80,150mm

21. Cryostat support structure Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu

22. Mechanical Integration(1) Main Requirements of the design: (1) Provide support and adjustments for all sub-detectors (2) Provide easy installation and reasonable gaps between neighboring sub-detectors both in radial and longitudinal directions. (3) Convenient access to sub-detectors for maintenance without breaking the accelerator vacuum. Door opening, Endcap EMC/TOF moving (4) The re-position of the end iron yoke should guarantee no change of the magnet field. (5) Provide route and space for cables, cooling pipes and gas pipes (6) Minimize the fringe field along beam direction Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu

23. Concept Design of BESIII Superconducting Magnet Mechanical Integration(2) BESIII Technical Review, Sep 16~18, 2002, Zian Zhu

24. Mechanical Integration(3) Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu

25. Mechanical Integration(4) Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu Barrel yoke: Max. Stress: 15.5 MPa Max. Deformation: 0.24 mm

26. Mechanical Integration(5) Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu Barrel Yoke Assembly Lifting: Max. Stress: 73 MPa Max. Deformation: 0.4 mm

27. Mechanical Integration(6) Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu Base: (in the middle of main beam) Max. Stress: 93.5 MPa Max. Deformation: 6 mm

28. Mechanical Integration(7) Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu Sub-detector support cylinder: Max. Stress: 98 MPa Max. Deformation: 0.5 mm

29. Acknowledgement Design group members: Prof. S.Xu, Prof. X.Liu, Prof. J.Bai, L.Wang, S.Han, C.Wei, Q.Ji, W.Song, H.Guo, L.Liu, Z.Hou KEK experts group: Prof. H.Tsuchiya, Y.Makida, H.Yamaoka. Superconducting Magnet & Mechanical Integration BESIII Technical Review, Sep 16~17, 2002, Zian Zhu Thanks!