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Author
CERN – Geneva – CHJacques.Dutour
14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland 1 / 16
MQW magnets: results from the measuring campaign (double aperture resistive quadrupoles for LHC)
Didier Cornuet Jacques Dutour Miguel Silva
Author
CERN – Geneva – CHJacques.Dutour
14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland 2 / 16
Topics to be presented:
- ‘MQW magnet’ characteristics
- Characteristics of the measurements
- Measuring sequences
- Results from the analysis of the measurements
- Conclusions
Author
CERN – Geneva – CHJacques.Dutour
14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland 3 / 16
-Quadrupole magnet: 48 installed,4 reserve), 6 MQW quadrupoles replace 1 superconducting quadrupole.- In cleaning insertions of LHC.- Normal conducting (high radiation levels)- Two apertures in a common yoke (space constraints in the tunnel).- Two different power connections : DF (MQWA) and FF (MQWB).- Precision between pole profiles: 1x10-4m (over a length of 3.1m)
Magnetic length [m] 3.1Apertures separation [mm] 224Aperture diameter [mm] 46
MQW magnet characteristics:
Author
CERN – Geneva – CHJacques.Dutour
14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland 4 / 16
Characteristics of the measurements
-120 measurements MQWA,90 measurements in MQWB 114 measurements in central position.- “Harmonic Coil” technique (using 5 coils in radial configuration)-“ Mole” (0.75 m) displaced manually with extension shafts (carbon fiber tube ) in 5 positions along the magnet.- 3 measurements (forwards and backwards) in each position for all the measuring currents.- DF measuring currents: 40A, 200A, 710A (nominal) and 810A- FF measuring currents: 40A, 200A and 600A (nominal)
- ‘Integrated field gradient’ measurement errors: ± 2 ‰ at 40A
(Gm.Lm) ± 1,5 ‰ at 200A
± 1 ‰ at 600A
- Sextupolar component: ± 2 units
- Other harmonics: ± 10 %
Author
CERN – Geneva – CHJacques.Dutour
14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland 5 / 16
Magnetic field lines
DF configuration FF configuration
- High saturation in some regions of the yoke, due to FF configuration, changes the quadrupole and sextupole components of the DF configuration. The values measured in DF1 at 40A, no longer correspond to real magnetic field values (2nd measuring sequence)
Measuring sequences
Author
CERN – Geneva – CHJacques.Dutour
14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland 6 / 16
Measuring sequences
Influence of the FF configuration: the measuring sequence had to be changed.
The magnets could be remeasured or we could introduce a correctionin the measured values:
-5 cycles not enough to fully magnetize (change ∫Gdl at low current).-Start measurements at high currents and then at low currents(remanent field stabilized, less change of ∫Gdl at low currents).- Change demagnetization cycles (-Imax/3 => -2/3 Imax). -FF mode before DF mode because of change ∫Gdl and sextupole components even after demagnetization (memory of FF mode).
Author
CERN – Geneva – CHJacques.Dutour
14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland 7 / 16
Improved demagnetization cycle
Measuring sequences
Author
CERN – Geneva – CHJacques.Dutour
14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland 8 / 16
Analysis of the measurements
Harmonic coefficientsMQWA: nominal current
Average Harmonic coefficientsMQWA - AP1 710A
0.06
5.77
0.05
-1.10
-0.05 0.97 0.03
-0.67
39.73
4.22
-10.00
-5.00
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
50.00
b3 a3 b4 a4 b5 a5 b6 a6 b10 a10
Harmonic coefficents
Ave
rag
e va
lue
[un
its]
Average Harmonic coefficients MQWA - AP2 710A
-5.64
-0.04
-1.12
-0.06 0.97 0.04
4.67
0.64
-38.86
0.10
-50.00
-45.00
-40.00
-35.00
-30.00
-25.00
-20.00
-15.00
-10.00
-5.00
0.00
5.00
10.00
b3 a3 b4 a4 b5 a5 b6 a6 b10 a10
Harmonic coefficents
Ave
rag
e va
lue
[un
its]
Author
CERN – Geneva – CHJacques.Dutour
14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland 9 / 16
Analysis of the measurements
Harmonic coefficientsMQWA: nominal current
Harmonic term b5 correlation with the b3 termMQWA 710A aperture 1
4
4.5
5
5.5
6
6.5
7
7.5
25 30 35 40 45 50
b3 harmonic term [units]
b5
har
mo
nic
ter
m [
un
its]
R2=0.6924
Harmonic term b5 correlation with the b3 termMQWA 710A aperture 2
-7.5
-7
-6.5
-6
-5.5
-5
-4.5
-4
-50 -45 -40 -35 -30 -25
b3 harmonic term [units]
b5
har
mo
nic
ter
m [
un
its]
R2=0.7843
Author
CERN – Geneva – CHJacques.Dutour
14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland 10 / 16
Analysis of the measurements
Harmonic coefficients
MQWB: nominal current
Average Harmonic coefficientsMQWB - AP1 600A
-0.03 0.03
-9.37
0.26
2.91 2.34
0.07
-1.07
1.020.03
-14.00
-12.00
-10.00
-8.00
-6.00
-4.00
-2.00
0.00
2.00
4.00
6.00
8.00
b3 a3 b4 a4 b5 a5 b6 a6 b10 a10
Harmonic coefficents
Ave
rag
e va
lue
[un
its]
Average Harmonic coefficientsMQWB - AP2 600A
-0.07 0.04
3.39
9.48
-0.43
0.08 -0.02
-2.16-0.99
1.00
-8.00
-6.00
-4.00
-2.00
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
b3 a3 b4 a4 b5 a5 b6 a6 b10 a10
Harmonic coefficents
Ave
rag
e va
lue
[un
its]
Author
CERN – Geneva – CHJacques.Dutour
14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland 11 / 16
Analysis of the measurements Magnetic length
MQWA:
MQWB:
AP1 & AP2Current [A] Lm [m]
40 3.127200 3.127710 3.109810 3.105
AP1 & AP2Current [A] Lm [m]
40 3.128200 3.128600 3.122
'Magnetic length' variation with the currentMQWB
3.100
3.105
3.110
3.115
3.120
3.125
3.130
3.135
0 100 200 300 400 500 600 700
Current [A]
Lm
[m
] AP1
AP2
'Magnetic length' variation with the currentMQWA
3.100
3.105
3.110
3.115
3.120
3.125
3.130
3.135
0 100 200 300 400 500 600 700 800 900
Current [A]
Lm [m
] AP1
AP2
fit line
Author
CERN – Geneva – CHJacques.Dutour
14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland 12 / 16
Main field gradient
MQWA:
MQWB:AP1 & AP2Current [A] Gm [T/m] TF [T/m.A]
40 2.10 0.0524200 10.33 0.0517600 30.60 0.0510
Current [A] Gm [‰]40 0.27
200 0.11600 0.14
Averages
AP1 & AP2Current [A] Gm [T/m] TF [T/m.A]
40 2.09 0.0523200 10.37 0.0518710 34.67 0.0488810 37.00 0.0457
Current [A] Gm [‰]40 1.71
200 0.39710 0.26810 0.26
Averages
'Transfer function' variation with the currentMQWB
0.0450
0.0460
0.0470
0.0480
0.0490
0.0500
0.0510
0.0520
0.0530
0 200 400 600 800 1000
Current [A]
TF
[ T
/m.A
]
AP1
AP2 (absolute)
'Transfer function' variation with the currentMWQA
0.0450
0.0460
0.0470
0.0480
0.0490
0.0500
0.0510
0.0520
0.0530
0 100 200 300 400 500 600 700 800 900
Current [A]
TF
[ T
/m.A
]
AP1
AP2
fitting curve
Analysis of the measurements
Author
CERN – Geneva – CHJacques.Dutour
14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland 13 / 16
Analysis of the measurements Main field gradient
Main field gradient of both apertures MQWA - 40A
2.080
2.085
2.090
2.095
2.100
2.105
2.110
0 10 20 30 40 50 60
Magnet's number
Gm
[ T
/m ]
AP1
AP2
Main field gradient of both apertures MQWB - 40A
2.080
2.085
2.090
2.095
2.100
2.105
2.110
0 10 20 30 40 50 60
Magnet's number
Gm
[ T
/m ]
AP1
AP2
Main field gradient of both apertures MQWA - 710A
34.50
34.55
34.60
34.65
34.70
34.75
34.80
34.85
34.90
0 10 20 30 40 50 60
Magnet's number
Gm
[ T
/m ]
AP1
AP2
Main field gradient of both aperturesMQWB - 600A
30.45
30.50
30.55
30.60
30.65
30.70
30.75
0 10 20 30 40 50 60
Magnet's number
Gm
[ T
/m]
AP1
AP2
Author
CERN – Geneva – CHJacques.Dutour
14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland 14 / 16
Analysis of the measurementsMagnetic centre driftIn horizontal plane
MQWA:- magnetic centres getfurther from each other
MQWB:- magnetic centres getcloser to each other
x' variation with the currentMQWA
-0.400
-0.300
-0.200
-0.100
0.000
0.100
0.200
0.300
0.400
0.500
0 200 400 600 800 1000
Current (A)
x'
[m
m]
AP1
AP2
x' variation with the currentMQWB
-0.400
-0.300
-0.200
-0.100
0.000
0.100
0.200
0.300
0.400
0.500
0 100 200 300 400 500 600 700
Current (A)
x'
[m
m]
AP1
AP2
Author
CERN – Geneva – CHJacques.Dutour
14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland 15 / 16
Analysis of the measurementsMain field direction
Average values: AP1 = 0.03 mrad ; AP2 = -0.08 mrad
Values are within the expected precision: ± 2 mrad
Main field directionMQWA nominal current
-0.002500
-0.002000
-0.001500
-0.001000
-0.000500
0.000000
0.000500
0.001000
0.001500
0.002000
0 5 10 15 20 25 30 35 40 45 50 55 60
Magnet's number
Bm
[ra
d]
AP1
AP2
Author
CERN – Geneva – CHJacques.Dutour
14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland 16 / 16
Conclusions
- The measured values are correct, within our expected errors: there’sno need of corrections (MQW magnets in cluster of 5, average improved).
- Each improvement made to get a better precision of the measurements,resulted in a longer time needed for the same measurements.
-If 10 magnets were measured only in ‘FF configuration’ and the other 42 magnets only in ‘DF configuration’ the measurement campaign time would have been much reduced, but the flexibility for the selection of the magnets would have been lost.