Experience from HQ coils CWG meeting F Borgnolutti

Experience from HQ coils CWG meeting F. Borgnolutti, D. Cheng 04/01/2014

Outline Ø Coil dimensions (pole gap, wedge gap, coil length) Ø Plasma coating 3/3/2021 2

Measurement Analysis: Pole Gap Total pole gap contraction (cable relaxation + reaction) Pole gap contraction (mm) Initial gap HQ 02 HQ 03 3. 5 Sleeve insulation Braided insulation 3. 0 2. 5 Average cable relaxation 2. 0 Sleeve insulation 1. 51 mm 1. 5 Braided insulation 1. 50 mm 1. 0 1024 1034 1021 1020 1034 1024 1034 1021 1034 0. 5 1020 1021 0. 0 -0. 5 Average coil contraction after reaction Sleeve insulation 1. 42 mm Braided insulation 0. 10 mm 15 16 17 18 19 20 21 22 23 24 25 26 Coil # Reproducibility (even with different cable) Ti doped cable (coil 18) has a similar gap contraction than Ta coils (all other) Difference in gap contraction after reaction likely due to the different type of insulation used. 3/3/2021 3

Pole gap in HQ 02 and HQ 03 coils Two possible explanations: Case 1) Braided insulation is tighter around the cable and therefore it could reduce the coil contraction (ends look less compacted with braided insulation) Case 2) Braided insulation is thicker and therefore it reduces the space left for the cable to expand. Target Sleeve Braid 100 um 90 um 104 um Azimutal room left for cable expansion 4. 5% 6. 0% 3. 9% Radial room left for cable expansion 1. 5% 1. 6% 1. 4% Insulation thickness (@7 MPa) We do not know which one of these effect is dominant. However, the test of HQ 02 showed that coil 17 which has braided insulation performed as good as other coils which use sleeve insulation. 3/3/2021 4

An answer from SQXF? Ø In HQ we had a sleeve insulation too thin and a braided insulation too thick. Ø In SQXF we use a braided insulation which is 10 um smaller than the target! Gap contraction due to reaction (mm) Tentative projection to SQXF in the case where the amount of space left for the cable to expand is the cause: QXF cable HQ 1. 6 Insulation Room left HQ sleeve 1. 4 width for az expansion target 150 um 4. 5% actual 140 um 5. 8% 1. 2 1 SQXF? 0. 8 0. 6 0. 4 HQ braided 0. 2 0 0. 0 2. 0 4. 0 6. 0 Az room for cable to expand (% of the bare cable width) 8. 0 Wrt unreacted bare cable In the event were the room left for cable expansion is the cause then the gap reduction due to reaction in SQXF should be around 1. 3× 1. 01/0. 76 = 1. 7 mm If 1. 7 mm contraction is observed in SQXF 1 then this would point at the case 2. otherwise it is case 1. 3/3/2021 5

Wedge gap At High temperature: - Phosphore bronze expands twice as much as Titanium - We do not know by how much the coil expand/shrink Ti 6 Al-v 4 CTE Phosphore Bronz (from 20 to 650ºC) (From 20 to 300ºC) 9. 7 um/m/ºC 17. 8 um/m/ºC Total Ti growth (20 to 650ºC) : 6 mm/m Total Wedge growth (20 to 650ºC): 11 mm/m Before HT Very conservative case: 1) The Ti pole expands and close the pole gap. The wedge gap reduces due to wedge expansion. 2) Once the pole gap is closed the Ti pole continue to expand as temperature goes up, thus increasing the length of the coil. Minimum wedge gap = wedge_expansion – (Ti expansion – initial pole gap) Application to HQ: min wedge gap = 11*0. 76 -(6*0. 76 -3. 5) = 7. 4 mm 3/3/2021 6

Wedge to spacer gap Side B Layer 2 Side A Side B Side A Spacer/wedge gap (measured after winding/bef. curing ) Layer 1 side A 10 length [inch] Layer 1 9 Layer 1 -Side B 8 Layer 2 -side A 7 Average values Pole Gap Layer 2 -side B 6 : 3. 5 mm L 1 wedge gap : 4. 6 mm L 2 wedge gap : 5. 4 mm 5 4 3 2 1 0 13 14 15 16 17 18 19 20 21 22 23 24 25 26 coil number 3/3/2021 7

Wedge gap HQ works tentative extrapolation from HQ to SQXF HQ L_straight section = 0. 76 m QXF L_straight section = 1. 01 m HQ Pole Gap : 3. 5 mm L 1 wedge gap : 4. 6 mm 3/3/2021 SQXF? Pole Gap : 3. 5 × (1. 01/0. 76) = 4. 7 mm L 1 wedge gap : 4. 6 × (1. 01/0. 76) = 6. 1 mm 8

Coil length Coil Layer 1 and Layer 2 overall lenght after curing (from RE end saddle to LE splice block) 14. 0 L 1 & L 2 lengths - nominal (dwg) [mm] 12. 0 10. 0 HQ 03 Coil 21 L 2 HQ 02 ΔL 2~4 mm 8. 0 6. 0 ~5 mm ΔL 1=7 mm ~3 mm 4. 0 2. 0 0. 0 15 16 17 18 19 20 21 22 23 24 25 26 27 coil number On average coils are about 7 mm longer than what expected from the cad model 3/3/2021 9

Outline Ø Coil dimensions (pole gap, wedge gap, coil length) Ø Plasma coating 3/3/2021 10

Plasma coating Ø No short with plasma coated parts 14 HQ 03 HQ 02 15 After Curing L 1: RE spacer to coil short After Curing L 1: coil to RE end spacer 16 L 1: No shorts 17 L 1: No shorts 18 L 1: no short After Curing L 2: no short After curing L 2: Short between L 2 RE end spacer and coil (turn 15) L 2: No shorts (there was one who disappeared after putting the bushing blocks) L 2: lot of turn to turn short in turn 2, 3, 4, 5. No coil to parts and coil to tooling short. 19 Before curing L 1: short between the 4 th turn and the inner LE spacer. After curing L 1: the short descibed above is gone. A tooling short was created: it is located on the lead cable (goes away as we move the cable) Bfore curing L 2: Not turn to turn electrical short / a short between the outer surface of the L 2 RE spacer and the coil After curing L 2: still no turn to turn electrical short / the short between the L 2 RE spacer is gone 20 Before Curing L 1: short bwteen the coil and the RE spacer After Curing L 1: the short is gone Before and after L 2 curing: No part to coil short and no turn to turn short 21 Before Curing L 1: No short. After Curing L 1: No short. Before Curing L 2: No short. After Curing L 2: No short. 22 Before Curing L 1: No short. After Curing L 1: No short Before Curing L 2: No short After Curing L 2: No short Before Curing L 1: No short. After Curing L 1: No short Before Curing L 2: No short After Curing L 2: No short 23 24 25 26 3/3/2021 11

Plasma coating Ø Plasma spray coating applied manually but tolerances were met even though the curved face of the spacers was sometime slightly out of tolerance. Ø Coating thickness checked with a magnetic prob. Requirement 8 mils +/- 2 mils Except on the flat faces were we asked for 9 mils +/- 1 mils Ø On average we got 8 mils +/- 2 mils 3/3/2021 12

Plasma coating Ø Detachment of the coating observed after the curing operation: It could be that the surface was not properly prepared before the coating was applied. 3/3/2021 13

Thank you 3/3/2021 14