MQXF cable with RRP wires for Q2 Luc Oberli MQXF Cable Review Nov. 5, 2014 05/11/2014 Luc Oberli

Outline 1st Part: Overview on the main results obtained on the MQXF cables fabricated before to arrive to the “first iteration” cable parameters. Experience with the MQXF cable fabrication Status of the cable performance concerning the critical current degradation during cabling. 2nd Part: Development program to improve the mechanical stability of the cable. 3rd Part: MQXF cable fabricated with RRP 132/169 wire for the first quadrupole model Status of the MQXF cable fabrication for the first quadrupole model Analysis of the results obtained on the MQXF cables fabricated with RRP 132/169 wire Conclusion 05/11/2014 Luc Oberli

“First iteration” cable parameters Mid-thickness = 1.525 mm +/- 0.010 mm Width = 18.15 mm +/- 0.050 mm Keystone angle = 0.55 deg. +/- 0.10 deg. Pitch Length = 109 mm +/- 3 mm S.S. core width = 12 mm Core thickness = 25 mm t Strain : 1 – (t/2d) Thin edge 15.4 % Thick edge 5.2 % 05/11/2014 Luc Oberli

1st part Experience with the MQXF cable fabrication CERN’s experience based on 16 different cabling runs dedicated to the MQXF cable fabrication Fabrication of 4 cables with the “first iteration” dimensions with RRP 132/169 wire for the quadrupole model program (4 cabling runs and in total 650 m of cable). Fabrication of 14 RRP cables and 10 PIT cables with different parameters during the R&D program before to arrive to the “first iteration” parameters for the cable (10 cabling runs and in total 250 m of cable). Variation of width, mid-thickness, keystone angle and transposition pitch in the following range: During the winding tests, all the cables were NOT sufficiently mechanically stable Measured average Ic degradation for 10 RRP cables between 0.5 % and 7.8 % RRR of extracted RRP strands above 97. 05/11/2014 Luc Oberli

Analysis of the results obtained for 10 cables fabricated with RRP 132/169 wire before to arrive to the “first iteration” parameters for the cable Run ID Cable width Keystone angle Mid-thickness Pitch length 1 – (t/2d) Strain thin edge Ic Degradation (average) RRR Extracted Virgin 82 17.8 mm 0.65 1.50 mm 113 mm 17.7 % 1.8 % 137 168 1.53 mm 16 % 2.9 % 143 125 mm 0.5 % 2.6 % 126 3.8 % 132 90 0.67 1.534 mm 109 mm 15.8 % 2.5 % 112 268 0.66 17.8 % 5 % 122 92A 18.1 mm 0.62 1.512 mm 16.8 % 2.4 % 115 93A 0.58 1.479 mm 18.3 % 2.7 % 97 97B 0.54 1.520 mm 15.2 % 7.8 % 176 239 Low critical current degradation for most of the cables with the exception of the cable 97B having a quite high degradation of 7.8 % . The RRR values of the extracted strands from the RRP cables are quite sensible to the cabling deformation at the level of the thin edge, but the RRR values stay above 97. 05/11/2014 Luc Oberli

Critical current degradation of the extracted strands from 10 RRP cables fabricated before to arrive to the “first iteration” cable parameters 50 Ic measurements performed on extracted strands (~ 5 Ic per cable) to evaluate the Ic degradation depending of the cable parameters. Ic degradation in a range between 0 and 9 % 05/11/2014 Luc Oberli

Analysis of the critical current degradation obtained for the cables 92A and 97B Ic degradation measured on extracted strands from these two RRP cables. Ic Degradation run 92A : 3.3 %, 1.6 %, 4.9 %, 0 % (average = 2.7 %) Ic Degradation run 97B : 3.3 %, 8.5 %, 6.5 %, 4.3 %, 9.2 %, 7.5 % (average = 7.8 %) Cable 92A Shearing of the sub-elements can be seen in the strands located at the cable thin edge for both cables. Cable 97B 05/11/2014 Luc Oberli

Analysis of the results obtained for 10 cables fabricated with RRP 132/169 wire before to arrive to the “first iteration” parameters for the cable Run ID Cable width Keystone angle Mid-thickness Pitch length 1 – (t/2d) Strain thin edge Ic Degradation (average) RRR Extracted Virgin 82 17.8 mm 0.65 1.50 mm 113 mm 17.7 % 1.8 % 137 168 1.53 mm 16 % 2.9 % 143 125 mm 0.5 % 2.6 % 126 3.8 % 132 90 0.67 1.534 mm 109 mm 15.8 % 2.5 % 112 268 0.66 17.8 % 5 % 122 92A 18.1 mm 0.62 1.512 mm 16.8 % 2.4 % 115 93A 0.58 1.479 mm 18.3 % 2.7 % 97 97B 0.54 1.520 mm 15.2 % 7.8 % 176 239 Low critical current degradation for most of the cables with the exception of the cable 97B having a quite high degradation of 7.8 %, no explanation was found why the Ic degradation of the cable 97B increased to 7.8 %. The RRR values of the extracted strands from the RRP cables are quite sensible to the cabling deformation at the level of the thin edge, but the RRR values stay above 97. Conclusion : all these results indicate that the strain at the cable thin edge shall not exceed 16 %. 05/11/2014 Luc Oberli

2nd part Development program to improve the mechanical stability of the cable Cable design for the cable development program The new cable parameters were chosen with the goal to improve the mechanical stability of the cable for winding and to decrease the critical current degradation To improve the mechanical stability of the cable for winding, the keystone angle was decreased to 0.4 degree in order to increase the strain at the cable thick edge. To minimize the Ic cable degradation, the mid-thickness of the cables was fixed to a value such that the strain at the cable thin edge doesn’t exceed 15.3 %. For the PIT cable, the strain thin edge was even decreased to 13.1 %. Strand type Keystone angle Mid-thickness Strain thin edge Strain thick edge RRP 0.36o 1.499 mm 15.2 % 8.5 % PIT 0.40o 1.540 mm 13.1 % 5.7 % 1.524 mm 14.1 % 6.6 % 0.39o 1.501 mm 15.3 % 8.1 % Baseline 0.55o 1.525 mm 15.4 % 5.2 % 05/11/2014 Luc Oberli

Results of the winding tests done with cables having a keystone angle of 0.4 degree to assess the mechanical stability of the cable The keystone angle was reduced to 0.4 degree to compact more the thick edge of the cable while compacting the thin edge less than 15.3 %, in particular for the PIT cables. Sample Cable ID Core Strand Width (mm) Mid-thickness (mm) Strain thin edge (1-t/2d) Pitch length Winding test in unfavourable direction without tool Winding test in unfavourable direction with tool 1 H16OC0165A Yes RRP 18.09 1.499 15.2 % 109 unstable stable 2 H16OC0166AA PIT 1.540 13.1 % 3 H16OC0166AB 1.524 14.1 % 4 H16OC0166AC 1.5013 15.3 % The cables are stable only with the tool in the unfavourable direction. A very slight tendency of a strand pop out on the outer surface of the cable is noticed only at the end of the turn, but most of the time the strand pop out disappears by itself. Conclusion: For the RRP cable, the decrease of the keystone angle to 0.4 degree brings more stability to the cable (but the tool remains essential for winding) and should diminish the risk to have a strand pop out during winding of the outer layer coil. 05/11/2014 Luc Oberli

Status of the QXF cable fabrication done with RRP 132/169 wire for the first quadrupole model Run ID Strand Type Core width Cable width Keystone angle Mid-thickness 113A Reduced Sn 14 mm 18.14 mm 0.57o 1.5237 mm 120A Low cost 18.13 mm 0.56o 1.5257 mm 121A Regular Sn 1.5260 mm 121B 12 mm 0.575o 1.5227 mm Baseline 18.15 mm 0.55o 1.525 mm Core not perfectly centred within the cable. Always a tendency to move toward the cable thick edge. 05/11/2014 Luc Oberli

Analysis of the results obtained for the cables fabricated with RRP 132/169 wire for the first MQXF model. Heat treatment for all the cables: 50 hours at 640 C RRP wire with regular Sn content except for the run 113A (reduced Sn) Run ID Cable width Keystone angle Mid-thickness Pitch length 1 – (t/2d) Strain thin edge Ic Degradation (average) RRR Extracted Virgin Cable Ic Calculated from Ic of extracted strands 113A 18.15 mm 0.57 1.524 mm 109 mm 15.7 % 3.5 % 257 354 25760 A 121A 18.14 mm 0.56 1.526 mm 15.5 % 3.2 % 194 291 25840 A 121B 0.575 1.523 mm 2.8 % 191 25940 A 122B 18.09 mm 0.36 1.499 mm 15.2 % 3.1 % 161 280 26424 A All the Ic values for the four cables are greater than 25 280 A (40 * 632 A) Specified Ic of the wire at 12 T and 4.2 K : 632 A 05/11/2014 Luc Oberli

Analysis of the critical current degradation obtained on the 18 Analysis of the critical current degradation obtained on the 18.15 mm wide cable Heat treatment used for all the cables : 48h/210C + 48h/400C + 50h/640C RRP strand with regular Sn was used in the fabrication of all cables, with the exception of the run 113A. Ic degradation measured on extracted strands. Ic degradation values are in a range between 0 % and 6.4 % Degradation run 113A : 3.4 %, 0 %, 4.3 %. 6.4 % (average = 3.5 %) Degradation run 121A : 2.4 %, 4.65 %, 2.8 %, 3.1 % (average = 3.2 %) Degradation run 121B : 0.5 %, 6 %, 0 %, 4.7 % (average = 2.8 %) Run 121A Run 113A Run 121B Shearing of the sub-elements clearly seen in the RRP strands located at the cable thin edge. 05/11/2014 Luc Oberli

Analysis of the RRR results obtained on the 18.15 mm wide cable Heat treatment used for all the cables : 48h/210C + 48h/400C + 50h/640C Most of the RRR measurements were made on 8 cm long samples from extracted strands having two deformed sections corresponding to the thin edge and thick edge of the cable. Run 113 : RRR = 228, 234, 309, 258, 259, 259 (RRR virgin 350) Run 121 A: RRR = 170, 180, 182, 199, 209, 222 (RRR virgin 291) Run 121 B: RRR = 171, 174, 186, 200, 207, 208 (RRR virgin 291) 05/11/2014

Analysis of the RRR results obtained on the 18.15 mm wide cable Local RRR values measured on extracted strands at the level of the thin edge or at the level of the thick edge of the cable are more relevant to evaluate the effect of cabling in order to qualify the cable. (Local RRR dominates electrical stability) Local RRR measurements performed on four extracted strands from the cable 113A. (RRP wire with reduced Sn content) Reduction of the RRR at the level of the thin edge section, but RRR remains largely above 100 Local RRR : 149 , 196, 182, 178 Thick edge Thin edge 05/11/2014 Luc Oberli

Analysis of the RRR results obtained on the 18.15 mm wide cable Local RRR measurements performed on seven extracted strands from the two cables 121A and 121B Sharp reduction of the RRR at the level of the thin edge section, but RRR remains above 100 Local RRR : 106, 118, 120, 167, 117, 130, 124 Thick edge Thin edge 05/11/2014 Luc Oberli

Analysis of an heavy deformed strand from the cable 121A and 121B From time to time along the cables, heavy deformed strands were detected at the level of the thin edge. These extracted strands were selected to determine the value of the local RRR. The distance between the voltage taps was reduced to ~ 2 mm to measure the local RRR of the abnormally squeezed strand at the level of the thin edge. 05/11/2014 Luc Oberli

MQXF cables fabricated with RRP 132/169 wire Conclusion MQXF cables fabricated with RRP 132/169 wire for the first quadrupole model and with the “first iteration” cable parameters were fully qualified Performances well within the expectations concerning the average Ic degradation of the cable which is below 5 %. Local RRR of the cable thin edge above 100, but the starting value of the RRR of the virgin wire was above 250. In the worst case, the local RRR can drop to 87. To better control the reduction of the RRR at the cable thin edge, preferable to have a thin edge thicker by 30 micrometers. 05/11/2014 Luc Oberli