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

2. 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

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

4. 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

5. 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

6. 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

7. 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 : %, 1.6 %, 4.9 %, 0 % (average = 2.7 %)
Ic Degradation run 97B : %, 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

8. 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

9. 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

10. 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

11. 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 mm
120A
Low cost
18.13 mm
0.56o mm
121A
Regular Sn mm
121B
12 mm
0.575o 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

12. 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 A (40 * 632 A)
Specified Ic of the wire at 12 T and 4.2 K : 632 A
05/11/2014
Luc Oberli

13. Analysis of the critical current degradation obtained on the 18
Analysis of the critical current degradation obtained on the 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 : %, 0 %, 4.3 %. 6.4 % (average = 3.5 %)
Degradation run 121A : %, 4.65 %, 2.8 %, 3.1 % (average = 3.2 %)
Degradation run 121B : %, 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

14. 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

15. 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

16. 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

17. 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

18. 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