Brouwer Lawrence Berkeley National Laboratory Berkeley CA USA December 11 th 2012 The CantedCosineTheta Dipole CCT For LBNL High Field Magnet Program PhD student UC Berkeley ID: 1045853
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1. Shlomo Caspi and Lucas Brouwer*Lawrence Berkeley National Laboratory, Berkeley, CAUSADecember 11th 2012The Canted-Cosine-Theta Dipole (CCT)For LBNL High Field Magnet Program* PhD student UC BerkeleyEDMS 1259004
2. Superconducting Magnet Program (SMP)LBNL Superconducting base program R&D on high field magnets is exploring a new dipole magnet (CCT) that specifically promises to reduce high stress on coils while maintaining field quality and efficiency. Diego Arbelaez, Lucas Brouwer, Daniel Dietderich, Helene Felice, Ray Hafalia, Etienne Rochepault, Soren PrestemonArno Godeke, Dan Cheng, Xiaorong Wang, Abdi Salehi, Charles Swenson, Tiina Salmi2Superconducting Magnet Group - S.Caspi12/11/2012
3. OutlineIntroductionShort historical perspective of high field accelerator magnetsThe Canted-Cosine-Theta (CCT) – A new approachThe CCT and the present LHC dipoleA conceptual 18T CCT dipole magnetOther CCT applicationsConclusions3Superconducting Magnet Group - S.Caspi12/11/2012
4. 33 years of progress in Nb3Sn technologyAn historical perspective:1979-20124Superconducting Magnet Group - S.Caspi12/11/2012Target
5. Introduction -Types of superconducting dipoles 5Superconducting Magnet Group - S.Caspi12/11/2012D20RD seriesHD series2D view
6. Introduction -Types of superconducting dipoles Block with stress managementManaged coil blocks, plates and laminar spring Direction of currentNewCanted-Cosine-Theta (CCT)With stress interception6Superconducting Magnet Group - S.Caspi12/11/2012TAMU 3D view
7. The CCT - History of the conceptPublished paper by D.I. Meyer and R. Flasck in 1970(D.I. Meyer, and R. Flasck “A new configuration for a dipole magnet for use in high energy physics application”, Nucl. Instr.and Methods 80, pp. 339-341, 1970.)Renewed interest during the past decade7Superconducting Magnet Group - S.Caspi12/11/2012
8. CCT MotivationSubstantial reduction in coil stressNo accumulation of Lorentz forces in the windingsSmall and large aperturesA high field quality over 85% of the bore.Intrinsic to the geometryA Modular concept with nesting different conductor typesOne style fits allNatural for gradingCombined function8Superconducting Magnet Group - S.Caspi12/11/2012
9. The CCT dipole cross-section9Superconducting Magnet Group - S.Caspi12/11/2012Areas of current are proportional to cos-theta approaching a perfect dipole current density distribution
10. The CCT coil terminationLambertson-Coupland TerminationHarmonic components over such “ends” integrate to zero 10Superconducting Magnet Group - S.Caspi12/11/2012
11. “Ends” - Termination HarmonicsDipole field Sextupole integrates to zeroDecapole integrates to zero11Superconducting Magnet Group - S.Caspi12/11/2012
12. CCT – Stress InterceptionStress interceptors (Ribs), thin on the mid-plane thick at the polesSingle conductor turnRibs are part of the stress collector (Spar)12Superconducting Magnet Group - S.Caspi12/11/2012
13. Structural Interception – airplane wing The lift force to the skin is transfer to ribs that are tied to a spar connected to the fuselageMAIN SPARTies all theRIBS togetherRIBSTransfers the skin loads to the SPAR13Superconducting Magnet Group - S.Caspi12/11/2012
14. Splitting the force and intercepting StressThe Lorentz force is split into two orthogonal components:The Lorentz forces along the coil’s surface (azimuthal and axial, not only in theta) are intercepted by ribs (no accumulation)Intercepted forces are carried by the spar to which the ribs are connectedThe radial Lorentz force are partially restrained by the spars and an outer structureRibs and Spars = “Cable-in-Conduit”14Superconducting Magnet Group - S.Caspi12/11/2012
15. Example: a CCT type LHC dipole15Superconducting Magnet Group - S.Caspi12/11/2012Same bore size and cable as LHC dipole ! bore [mm]15.35 ! Layer 1 width [mm]2.15 ! Layer 1 thick [mm]1.25 ! Layer 1 keystone angle [deg]15 ! Layer 1 tilted angle [deg]0.45 ! Layer 1 mid-plane rib thickness) [mm] 0.2857 ! Layer 1 Asc/Acable 15.35 ! Layer 2 width [mm]1.73 ! Layer 2 thick [mm]0.9 ! Layer 2 keystone angle [deg]12.54 ! Layer 2 tilted angle [deg]0.45 ! Layer 2 mid-plane rib thickness) [mm] 0.2462 ! Layer 2 Asc/Acable Same straight section of 0.7m using 41m of cable
16. Example: a CCT LHC dipole16Superconducting Magnet Group - S.Caspi12/11/2012 Field Field quality Stored Energy Stress Conductor lengthComparison of a canonical LHC dipole with an equivalent CCT56mm137137693CoilRibs and Spar
17. Short-sample comparison at 1.9 KShort-SampleLHCWith-IronCCTWith-Iron56 mm bore, 2 layers, same cablesB0 (T)9.79.2Bmax (T)10.09.6Imax (kA)13.815.67Je (A/mm^2)419475E (kJ/m)334294Inductance (mH/m)3.482.39*Stheta (MPa)88 ~ 8* Courtesy of Jeoren Van Nugteren17Superconducting Magnet Group - S.Caspi12/11/2012 Lower field, proportional to slanted angle cos(15)=0.966 Low stress Similar stored energy and inductance Similar conductor lengthFor this comparison we chose to keep the same bore, number of layers, strand sizes and cable sizes.Choosing other parameters would have raise the field.
18. CCT 18Superconducting Magnet Group - S.Caspi12/11/2012Field (Bmod) around inner boreField (Bmod) between layers
19. CCT – Harmonics (no-iron)19Superconducting Magnet Group - S.Caspi12/11/2012CCT - less than 2 units at 85% of the boreLHC b3 ~ 3 unitsb5 ~ -1 unit
20. Field profiles along the z axis20Superconducting Magnet Group - S.Caspi12/11/2012No iron
21. Stress on Ribs and SparTurnRibsRadial Stress ~ Cos(theta)Normal Stress~ Sin(theta)21Superconducting Magnet Group - S.Caspi12/11/2012Radial forces are intercepted by spars and structure
22. Modeling and Minimum symmetryCoilSpar with RibsCoil Minimum Symmetry22Superconducting Magnet Group - S.Caspi12/11/2012
23. LaminationRibsConductor23Superconducting Magnet Group - S.Caspi12/11/2012Lamination can simplify analysisReduce costReduce losses
24. Lamination - 10.05 mm thick24Superconducting Magnet Group - S.Caspi12/11/2012Ribs and SparCoilCoil Ribs and SparThe lamination hold exactly one turn of coil, rib and spar
25. Lamination25Superconducting Magnet Group - S.Caspi12/11/2012
26. Laminated Model in TOSCA Bmod (14.85 kA)26Superconducting Magnet Group - S.Caspi12/11/2012
27. Mechanical Analysis27Superconducting Magnet Group - S.Caspi12/11/2012We have just started stress analysis on the coil ribs and spar.Need to demonstrate that stress interception works, the force carried by the spar and the ribs should withstand the forceThree mechanical models in progressANSYS Workbench one lamination at 10T and 20T ANSYS Classical - one laminationCASTEM– one turn at 10T and 20T
28. Workbench - Ribs and Spar10T - Axial deformation spar and ribs28Superconducting Magnet Group - S.Caspi12/11/201220T – Azimuthal stress spar and ribs
29. CASTEM Model – 20T frontbehindRib + ring + coil Axial displacement29Superconducting Magnet Group - S.Caspi12/11/2012CoilRibSpar (3mm)Von-Mises Stress (MPa)0-550-200200-400Coil Von-Mises Stress
30. Example – 6 layers 18T dipole, 56mm bore 3D analysis, no iron 6 layers graded. Coil is 60mm thick (no spars*) Current 10.5 kA Bore field 18 T at 1.9K Intercepted stress < 30MPa30Superconducting Magnet Group - S.Caspi12/11/2012
31. Example – 6 layers 18T dipole, 56mm boreLayer 1, 30 strandsLayer 2, 26 strandsLayer 3, 22 strandsLayer 4, 18 strandsLayer 5, 14 strandsLayer 6, 12 strands56mm31Superconducting Magnet Group - S.Caspi12/11/2012 Proof of principle Spars omitted* Spars and stress analysis will be next* Adding spars of any size will not change the field in the bore
32. Example – Load lines (no iron)Stored Energy:18T10.5kA2.22 MJ/m44 mH/m32Superconducting Magnet Group - S.Caspi12/11/2012
33. Field along the magnet center33Superconducting Magnet Group - S.Caspi12/11/2012
34. Mid-plane Stress - without interception34Superconducting Magnet Group - S.Caspi12/11/2012The mid-plane stress in each of the layers if the Lorentz force is not intercepted
35. Normal stress cable-rib - with interceptionTangential Stress (Normal to Rib)35Superconducting Magnet Group - S.Caspi12/11/2012The Lorentz stress in each of the layers if the Lorentz force is intercepted
36. Other Applications – A curved CCT dipole for a gantry36Superconducting Magnet Group - S.Caspi12/11/2012*D. S. Robin, C. Sun, A. Sessler, W. Wan, M. Yoon
37. A “pure” dipole fieldBd=5T37Superconducting Magnet Group - S.Caspi12/11/2012
38. A “pure” quadrupole fieldG=-25T/m,Single layer Double layers 38Superconducting Magnet Group - S.Caspi12/11/2012
39. A “pure” sextupole fieldS=400 T/m2Double layers Single layer 39Superconducting Magnet Group - S.Caspi12/11/2012
40. Combined Function - Dipole+Quad+Sextupole Bd=5T, G=-2.26T/m, S=1.3 T/m240Superconducting Magnet Group - S.Caspi12/11/2012
41. Other Applications – ECR41Superconducting Magnet Group - S.Caspi12/11/2012
42. SummaryA New Magnet Type – Canted-Cosine-ThetaGeneric design – for all NbTi, Nb3Sn, HTS, simplified toolingStress interception not accumulation (independent of the # of turns)A linear structure (not dominated by conductor Young’s modulus)High field quality over an extended range (no optimization, better quality)Magnet “end harmonics” naturally integrate to zero (no end spacers)Combined function field, (offsets in geometric errors included)Islands and wedges replaced by ribsGrading using a single strand with different cables, hybrids Nb3sn+HTSPossible no conductor insulation (to ground only, ceramic coating) Extended technology to curved coils and other type magnets42Superconducting Magnet Group - S.Caspi12/11/2012
43. Need to ExploreFabrication: Nb3Sn dimensional changes during heat treatment Electrical integrity (conductor to spar)Mechanics:Structure, pre-stress, cool-down Shear stress at interfaceProtection:protection scheme protection heaters and other instrumentationShort-sample and training43Superconducting Magnet Group - S.Caspi12/11/2012
44. Possible Next StepsSubscale demonstrators – a 3T-4T, 56mm bore NbTi dipoleSubscale demonstrators – a small bore HTS dipole (YBCO)Subscale demonstrators – a 12T, 56mm bore Nb3Sn dipoleA full scale ~20T design 44Superconducting Magnet Group - S.Caspi12/11/2012
45. Selected References D. S. Robin, D. Arbelaez, S. Caspi, A. Sessler, C. Sun, W. Wan, and M. Yoon, Nucl. Instrum. Meth. Phys. Res.A 659 (2011) 484-493.S. Caspi, D. Arbelaez, H. Felice, R. Hafalia, D. Robin, C.Sun, W. Wan and M. Yoon, Conceptual Design of a 260 mm Bore 5T Superconducting Curved Dipole Magnet for a Carbon Beam Therapy Gantry, IEEE Trans. Appl. Superconduct., Vol. 22, no. 3, p. 4401204, (2012).C. Sun, D. Arbelaez, S. Caspi, D. Robin, A. Sessler, W. Wan and M. Yoon, Compact beam delivery system for ion beam therapy, Proceedings of IPAC2011, San Sebastian, Spain p. 3633-3635 (2011).S. Caspi, D. Arbelaez, L. Brouwer, D. Dietderich, R. Hafalia, D. Robin, A. Sessler, C. Sun, and W. Wan, Progress in the Design of a Curve Superconducting Dipole for a Therapy Gantry, Proceedings of IPAC2012, New Orleans, Louisiana, p. 4097-4099 (2012).D.I. Meyer, and R. Flasck, A new configuration for a dipole magnet for use in high energy physics applications, Nucl. Instrum. Meth., pp. 339-341, 1970.C.L. Goodzeit, M.J. Ball, and R.B. Meinke, The Double-Helix dipole-a novel approach to accelerator magnet design, IEEE Trans. Appl. Superconduct., Vol. 13, no. 2, pp. 1365-1368, June 2003.A.V. Gavrilin, et al.,New concepts in transverse field magnet design, IEEE Trans. Appl. Supercond.,Vol.13, no. 2, pp.1213-1216,June 2003.A. Devred, et al., Overview and status of the next European dipole joint research activity, Supercond. Sci. Technol. 19, pp 67-83, 2006.C. Goodzeit, R. Meinke, M. Ball, Combined function magnets using double-helix coils, Proceedings of the Particle Accelerator Conference, 2007 PAC IEEE, pp. 560-562, 2007.S. Caspi, D.R. Dietderich, P. Ferracin, N.R. Finney, M.J. Fuery, S.A. Gourlay, and A.R. Hafalia, Design, Fabrication, and Test of a Superconducting Dipole Magnet Based on Tilted Solenoids, IEEE Trans. Appl. Supercond, Vol. 17, part 2, pp. 2266-2269, 2007.H. Witte, T. Yokoi, S.L. Sheehy, K. Peach, S. Pattalwar, T. Jones, J. Strachan, N. Bliss, The Advantages and Challenges of Helical Coils for Small Accelerators-A Case Study, IEEE Transactions on Applied Superconductivity, Vol. 2, p. 4100-4110 (2012)S. Caspi, S. Gourlay, R. Hafalia,, A. Lietzke, J. O'Neill, C. Taylor and A. Jackson, The use of pressurized bladders for stress control of superconducting magnets, IEEE Trans. on Appl. Superconductivity, Vol, 11, no 1, p. 2272-2275 (2001).S. Caspi, D. Arbelaez, L. Brouwer, D. R. Dietderich, H. Felice, R. Hafalia, D. Robin, C.Sun, W. Wan, A Canted Cosine-Theta Curved Superconducting Dipole Magnet for a Particle Therapy Gantry, Nucl. Instrum. Meth. To be published 2012/13L. J. Laslett, S. Caspi, and M. Helm, Configuration of coil ends for multipole magnets, Particle Accelerators, 1987, Vol. 22, pp. 1-14.45Superconducting Magnet Group - S.Caspi12/11/2012