HL-LHC Corrector Magnet Design & Construction Activity Status

1. HL-LHCCorrector MagnetDesign & ConstructionActivity Status Giovanni Volpini on behalf of the LASA team CERN, January 14 2014

2. summary • Magnet specs requirements: integrated field, radiation loads & material certification operating features: operating currents, size • Cross section design 2D from 2- to 6- pole • Load lines, margins • Superconducting wire choice, insulation & impregnation scheme, protection • Mechanical issues assembly • Problems waiting for us just round the (3D) corner… magnetic length cross-talk between magnets fringe field (“harmonics” at the magnet ends) forces between magnets Giovanni Volpini, CERN 14 January 2014

3. magnet specs & operating features Giovanni Volpini, CERN 14 January 2014

4. Cross-sections Quadrupole yoke coil bore recooler pipe coil Sextupole yoke bore Giovanni Volpini, CERN 14 January 2014

5. 2D cross sections: 4-pole Yokeradius = 230 mm Warning: no strayfield Jeng (overall) ~ 300 A/mm² Bpeakiron = 2.43 T Bpeak coil = 2.82 T Recooler bore D 50 mm @ r = 190 mm Giovanni Volpini, CERN 14 January 2014

6. 2D cross sections: 6-pole Yokeradius = 160 mm Bpeakiron = 3.7 T Jeng (overall) ~ 260 A/mm² Bpeak coil = 2.0 T Recooler bore D 50 mm @ r = 190 mm, so it’soutside the yoke 03.12.2013 p 140 Giovanni Volpini, CERN 14 January 2014

7. 2D cross sections: 8- pole Yokeradius = 160 mm Jeng (overall) ~ 260 A/mm² Recooler bore D 50 mm @ r = 190 mm, so it’soutside the yoke 8-pole Bpeakiron = 2.5 T Bpeak coil = 1.8 T Giovanni Volpini, CERN 14 January 2014

8. 2D cross sections: 10- 12- pole Yokeradius = 160 mm Jeng (overall) ~ 260 A/mm² Recooler bore D 50 mm @ r = 190 mm, so it’soutside the yoke 10-pole Bpeakiron = 2.65 T Bpeak coil = 1.8 T 12-pole Bpeakiron = 2.8 T Bpeak coil = 1.8 T Giovanni Volpini, CERN 14 January 2014

9. SC wires - Small wire (low operating current), but not too small (must be easy to handle, insulation should not reduce too much the Je); - High Cu content (again, low operating current, protection (4-pole)); - From the shelf product (season sale?): small amount required (10’s of kg); - Small filament (not a strict requirement, but these magnets are designed to operate in the whole range 0-Imax; Bruker-EAS NbTi for Fusion application Fine filaments PF wires Wire type 2 Cu:NbTi≈ 2.30 Number of filaments 3282 Filament diameter≈ 8 μm @ 0.73 mm Two wire diameters: 0.5 and 0.7 mm S-glass insulation, An order for 8 km + 8 km will be issued in Jan 2014 Luvata Pori OK3900 Cu:NbTi ≈ 2.00 Number of filaments 3900 wire diameter 0.575 mm Filament diameter≈ 5.3 μm Bare wire An order for 20 km will be issued early in 2014 Giovanni Volpini, CERN 14 January 2014

10. Quadrupole load line Bpeak on coil Ic 350 A @ 5 T, 4.22 K Tcs = 5.9 K 1.9 K 4.22 K B @ r=50mm Design current = 300 A Giovanni Volpini, CERN 14 January 2014

11. 6- and 12-pole load lines Sextupole 1.9 K Ic 179 A @ 5 T, 4.22 K Bpeak on coil Dodecapole 4.22 K Sextupole B @ r=50mm Dodecapole Design current = 150 A Giovanni Volpini, CERN 14 January 2014

12. Field optimization Design current = 300 A a10 Geometrical harmonics are controlled by changing the pole profile from the ideal hyperbolic profile; no action has been taken to control saturation harmonics. Small effect in case we use non circular iron yoke profile. We fear that much larger harmonics will appear at the magnet ends when the 3D computations are made. a14 a9 Quadrupole Sextupole a6 a21 a15 Design current = 150 A Giovanni Volpini, CERN 14 January 2014

13. Magnet protection Quenchprotectionisbased on an externalresistordump. The maximum voltageVmaxisprovisionallyfixedat 100 V (6-pole to 12-pole) and 300 V (4-pole); anyinterest to keepVmax< 50 V? possible to raiseVmax> 300 V? protectiondoesnotrely on quenchheater; theycould be considered for test purposes; the peaktemperatures are computed in twolimiting case: vquench→ 0 (worst case) and vquench→∞ (limiting the quench to one coil only); quenchdetection and switchoperation time neglected; conclusion: quenchdoesnotseem a criticalpoint –notobvious, butlikely-; a more detailedquenchcomputation with properpropagationspeedhas to be performedwhen the design reachesitsfinal stage. Giovanni Volpini, CERN 14 January 2014

14. Insulation & impregnation scheme Polyimide: Neither European company is able to provide kapton insulated wire, at least for such small supplies; could not identify an external supplier for dip coating, but only tape coating; doubtful behaviour during impregnation w.r.t. fiberglass: is polyimide porous enough and does it stick well to the resin? Fiberglass: one wire supplier will provide the wire already insulated with S-2 glass, with a 0.14 mm total (i.e. on diameter) thickness; discussions in progress with a specialized company to study the insulation procedure for the bare wire; Impregnation CTD-101K seems to be the most used and well known resin system. We understand that its radiation endurance properties are compliant with the design requirement. We are starting to develop the impregnation procedure with this resin. Giovanni Volpini, CERN 14 January 2014

15. Assembly The coils are not in contact with the pole. The spacer and the pole profile are tapered to match closely the coil to the pole, beforetightening the screws of the wedge. wedge coil spacer pole Giovanni Volpini, CERN 14 January 2014

16. 3D design Sestupolepreliminary design Yokelaminationsmachined by laser cut followed by EDM (finalaccuracy 1/100 mm) on the relevantsurfaces: poles, coil slots, alignmentslots. Assuming 5.8 mm thickiron; placing an order in parallel to CERN one? Giovanni Volpini, CERN 14 January 2014

17. interfaces & interferences Alternative iron design for 6-to-12 pole, allowing better alignment and/or connection with the 4-pole and other magnets. Impact on field quality negligible. recooler pipe 6-8-10-12-pole ironradius 4-pole ironradius Iron radii used in the computations Mechanical & electrical connection between magnets and LHe vessel to be defined, along with room for bus-bars etc. Giovanni Volpini, CERN 14 January 2014

18. Winding and impregnation tooling: first tests Giovanni Volpini, CERN 14 January 2014

19. open issues summary Questions to be answered as soon as possible… • operating currents; • outer iron diameter & shape; • radiation hardness compliance, insulation & impregnation; • field quality & fringe field; • mechanical & electrical connection between magnets and LHe vessel to be defined, along with room for bus-bars etc.; …and, not to be forgotten: the MgB2 solution (playground) other solutions (combined function magnet)? Giovanni Volpini, CERN 14 January 2014

20. Next steps Design Problems waiting for us just round the (3D) corner… magnetic length cross-talk between magnets fringe field (“harmonics” at the magnet ends) forces between magnets (March 2014) Residual magnetization at I=0 and impact on the harmonics Cross check COMSOL results w/ Roxie (March 2014) Mechanical design (May 2014) Construction & test Wind & impregnate a dummy coil (June 2014) Design the test cryostat Giovanni Volpini, CERN 14 January 2014

21. End(Episode I) AcknowldgmentsPaolo FessiaRemi Gauthier Susana Izquierdo BermudezDavideTommasini… Giovanni Volpini, CERN 14 January 2014