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Agenda

EuCARD -HFM ESAC review of the high field dipole design FRESCA2 conceptual design Attilio Milanese 20 January 2011. Agenda. 2D design magnetic mechanical 3D design magnetic mechanical Extras (parametric analyses, what-if, details, …). Magnetic cross section. 1140 mm. 100 mm.

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Agenda

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  1. EuCARD-HFM ESAC reviewof the high fielddipole designFRESCA2conceptual designAttilio Milanese20 January 2011

  2. Agenda • 2D design • magnetic • mechanical • 3D design • magnetic • mechanical • Extras • (parametric analyses, what-if, details, …)

  3. Magnetic cross section 1140 mm 100 mm

  4. Magnetic cross section 156 turns (per pole) 36 + 36 + 42 + 42 Bcenter = 13.0 T I13 T = 10.5 kA Bpeak = 13.2 T 82.7 % load line @ 4.2 K 76.3 % load line @ 1.9 K [ 15.7 T s. s. 4.2 K 17.0 T s. s. 1.9 K ] DBy/Bcenter < 0.2 % (2/3 bore, Bcenter > 10 T) E = 3.58 MJ/m L = 46.8 mH/m

  5. Effect of the iron plus the effect on field quality

  6. What happens without prestress? Lorentz forces at 13 T: Fx,qua = 7.70 MN/m Fy,qua = −3.81 MN/m applied at warm with no prestress coil not glued to the poles displ. scale x 15 horiz. displ. ≈ 1.5 mm

  7. Structure, 2D potted coil The coil pack. Ti alloy iron Al bronze steel G10

  8. Structure, 2D The yoke and the shrinking cylinder. iron Al alloy 409 mm 70 mm 1000 mm

  9. Structure, 2D Structure partially prestressed at warm. potted coil Ti alloy iron Al bronze steel G10 Al alloy bladders

  10. Structure, 2D The full prestress is achieved at cold. potted coil Ti alloy iron Al bronze steel G10 Al alloy

  11. Prestress in the cross section • horizontal keys with 700 mm interference • vertical keys with 300 mm interference • Al alloy shell: I.D. = 1000, O.D. = 1140 mm • the bottom layers remain prestressed under excitation average stress between coil and pole layer 4 layer 3 layer 2 layer 1

  12. Stresses on the coil The potted coil stays below 150 MPa, the “comfort zone” for Nb3Sn. warm cold 13 T sx

  13. Coil geometry, 3D Total axial length of coil: 1500 mm about 730 mm of straight section easy way bend (no spacers) straight inclined straight 17 deg hard-way bend Rmin = 700 mm

  14. Field on coil without iron, 3D 14.6 T 13.9 T Without the iron there is field concentration on the ends (+ 0.7 T).

  15. Iron geometry, 3D yoke (laminations) 365 mm 135 top pole (solid piece) vertical pad (laminations)

  16. Field on the coil with iron, 3D Bcenter = 13.0 T I13 T = 10.2 kA Bpeak = 13.4 T The peak field is in the straight section.

  17. Magnetic field in the bore, 3D +2% +1% 0 −1% field on 100 mm diameter circle, z = 0 − 2%

  18. Plot of |B| on the axis The field on the axis is within 2% of the central field, almost for the all length of the straight section. no iron reference layout no extra block in vertical pad

  19. Structure, 3D

  20. Structure, 3D

  21. 3D stress effects • To be more investigated, in a full 3D FEM: • different thermal contractions • Poisson effect • axial preload • local effects on the coil • near the ends model with dummy coil

  22. Estimated weights Cailler of Switzerland, Sublim retails at 30 CHF/kg (for WS’ law)

  23. Thank you.

  24. Extras

  25. Extras: magnetic design 2D • only two layers closer to the midplane • only two layers farther away from the midplane • nonlinear sextupole • no iron in top pole • sensitivity analysis on multipoles • more / less turns? • a different cable / strand (modified HD2) • breakdown of Lorentz forces in 2D

  26. Extras: mechanical design 2D • pressure in the bladders • table of stresses in the structure • stresses in various components (pole pieces, • horizontal pad, vertical plate / pad, yoke, shell) • dimensioning the yoke and the shell • stresses on the coil, different friction among them • alternative coil pack structure, with inner tube • material properties for 2D analyses

  27. Only layers 1 & 2 • same current as for the • full dipole, 13 T case • same iron configuration I = 10.5 kA Bcenter = 8.0 T [8.0/13.0 = 61.5 %] Bpeak = 9.4 T 63.4 % load line @ 4.2 K 58.5 % load line @ 1.9 K [ 12.6 T s. s. 4.2 K 13.7 T s. s. 1.9 K ] b3 = 512.1 b5 = 20.0

  28. Only layers 3 & 4 • same current as for the • full dipole, 13 T case • same iron configuration I = 10.5 kA Bcenter = 6.8 T [6.8/13.0 = 52.3 %] Bpeak = 8.3 T 57.6 % load line @ 4.2 K 53.2 % load line @ 1.9 K [ 11.9 T s. s. 4.2 K 12.9 T s. s. 1.9 K ] b3 = −625.5 b5 = −64.4

  29. Nonlinear sextupole • due to the highly saturated iron close to the bore • (in particular, in the pole area) • the decapole b5 sees only ≈1 unit variation from 5 to 15 T

  30. No iron in top pole • no iron in top pole (only vertical pad and yoke) • that piece can make a difference • on the margin / short sample I = 10.8 kA Bcenter = 13.0 T Bpeak = 13.8 T 86.1 % load line @ 4.2 K 79.4 % load line @ 1.9 K [ 15.1 T s. s. 4.2 K 16.4 T s. s. 1.9 K ] b3 = 110.3 b5 = −19.1

  31. Sensitivity analysis on multipoles • current is kept the same (I = 10.5 kA) • same iron configuration

  32. More / less turns? • current changed to reach 13 T in the bore • same midplane thickness • same iron configuration • the turns are added / subtract on the far sides

  33. Different cable / strand? • HD2 naked cable dimensions used: 22.0 × 1.4 mm • but insulation kept at 200 mm • 51 strands 0.8 mm in diameter, but Cu/nonCu kept at 1.25 • same iron configuration (center blocks on top pole) • 188 turns instead of 156 (similar potted coil size) • according to and with the above • assumptions, only the filling factor k has an effect • the filling factor changes slightly, for this HD2 (modified) • case being about 2% lower than for the FRESCA2 cable • simulation confirms the guess: Bcenter = 13.0 T at I13 T = 8.7 kA • 83.6 % load line @ 4.2 K, 15.5 T s. s. 4.2 K (instead of 15.7 T) • inductance increase significantly, L = 68.5 mH/m (+46%) strong impact on k

  34. Lorentz forces in 2D 4 3 2 1 13 T

  35. Pressure in the bladders, 2D • for full prestress at 13 T, an horiz. interference of ≈ 700 mm is needed • add 100-200 mm for the clearance • interferences open for horizontal keys, pbladders = 10 MPa = 100 bar • wbladd = 75 mm (all the same)

  36. Stresses in the structure, 2D They are all within the yield values of the various materials. [At 15 T, about 33% more (pre)stress is needed.]

  37. Stresses on top and bottom poles seq cold cold, 13 T

  38. Stresses on horizontal pad / rails seq cold 13 T cold

  39. Stresses on vertical pad / plate cold cold, 13 T seq

  40. Stresses on yoke, part 1 cold cold, 13 T seq

  41. Stresses on yoke, part 2 cold cold, 13 T s1

  42. Stresses on shell cold cold, 13 T seqv

  43. Dimensioning the yoke and the shell • avg. pressure 3rd layer coil / pole, • for ix = 700 mm and iy = 300 mm • the (AA) shell thickness dictates • the prestress increase at cold • steel doesn’t buy enough at cold • aDT = 2.84∙10−3 vs. 4.02∙10−3 • stresses tend to go down when • there is more material, and “real • estate” is important chosen

  44. Stresses on the coil top / bottom sliding (friction 0.2) top / bottom glued warm cold 13 T sx It’s the same, as the contact is “sticking”.

  45. Alternative coil pack structure, 2D An inner steel support tube is present. potted coil Ti alloy iron Al bronze steel G10

  46. Material properties for 2D analysis ! potted Nb3Sn coil [1] mptemp,1,4.3,293 mpdata,ex,1,1,42000e6,30000e6 mpdata,prxy,1,1,0.3,0.3 mp,alpx,1,1.16E-5 !3.36e-3 ! stainless steel [2] mptemp,1,4.3,293 mpdata,ex,2,1,210000e6,193000e6 mpdata,prxy,2,1,0.28,0.28 mp,alpx,2,9.83E-6 !2.84e-3 ! aluminum bronze [3] mptemp,1,4.3,293 mpdata,ex,3,1,120000e6,110000e6 mpdata,prxy,3,1,0.3,0.3 mp,alpx,3,1.08E-5 !3.12e-3 ! iron [4] mptemp,1,4.3,293 mpdata,ex,4,1,224000e6,213000e6 mpdata,prxy,4,1,0.28,0.28 mp,alpx,4,6.82E-6 !1.97e-3 ! aluminum [5] mptemp,1,4.3,293 mpdata,ex,5,1,79000e6,70000e6 mpdata,prxy,5,1,0.34,0.34 mp,alpx,5,1.45E-5 !4.2e-3 ! G10 [6] mptemp,1,4.3,293 mpdata,ex,6,1,30000e6,30000e6 mpdata,prxy,6,1,0.3,0.3 mp,alpx,6,2.44E-5 !7.06e-3 ! Nitronic 40 [7] mptemp,1,4.3,293 mpdata,ex,7,1,225000e6,210000e6 mpdata,prxy,7,1,0.28,0.28 mp,alpx,7,0.90E-5 !2.6e-3 ! titanium [8] mptemp,1,4.3,293 mpdata,ex,8,1,120000e6,110000e6 mpdata,prxy,8,1,0.3,0.3 mp,alpx,8,6.25E-6 !1.8e-3

  47. Lorentz forces in 3D

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