1. 24/11/2017
Performance of the room temperature Systems for Magnetic Measurements of the LHC Superconducting Magnets at CERN
J. Garcia-Perez, J. Billan, M. Buzio, P. Galbraith, D. Giloteaux, V. Remondino
28/09/2005 J. GARCIA PEREZ
CERN – Geneva – CH
14th International Magnetic Measurement Workshop September 2005, Geneva, Switzerland

2. Outline Introduction Systems Description
24/11/2017
Outline
Introduction
Systems Description
Measurements and Analysis Overview
Performance:
Local and Integrated Dipole Field
High-order Harmonics
Field Angle
Experience Gained
Conclusions
28/09/2005 J. GARCIA PEREZ
CERN – Geneva – CH
14th International Magnetic Measurement Workshop September 2005, Geneva, Switzerland

3. People involved 24/11/2017 Search coils manufacture (LHC/AT-MTM)
R. Beltron, L. Gaborit
Mole manufacture (AT & EST/ME)
O. Dunkel, D. Cote, R. Camus, B. Girod, N. Mermillod, G. Patti, F. Fischer
Software (AB/CO) and data reduction and analysis (AT-MAS)
A. Rijllart, H. Reymond, A. Raimondo, E. Todesco, C. Vollinger, P. Hagen
Bench for the mole translation inside quadrupoles (CEA/ Saclay)
F. Simon
Operators who did many measurements at CERN and outside in the assembly firms
28/09/2005 J. GARCIA PEREZ
CERN – Geneva – CH
14th International Magnetic Measurement Workshop September 2005, Geneva, Switzerland

4. The DIMM mole Slip rings Incremental encoder Gravity sensor
24/11/2017
The DIMM mole
Slip rings
Incremental encoder
Gravity sensor
Rotating coils
Pneumatic brake
28/09/2005 J. GARCIA PEREZ
CERN – Geneva – CH
14th International Magnetic Measurement Workshop September 2005, Geneva, Switzerland

5. The search coils set for DIMM and QIMM
24/11/2017
The search coils set for DIMM and QIMM
Dipoles
Coils are 14.2 mm wide
3 coils per mole
25 moles built
MQ, MQM, MQY & correctors
Coils are 8.4 mm wide
5 coils per mole
12 moles built
MQW (resistive)
Coils are 7.4 mm wide
5 coils per mole
1 mole built
28/09/2005 J. GARCIA PEREZ
CERN – Geneva – CH
14th International Magnetic Measurement Workshop September 2005, Geneva, Switzerland

6. Mole translation devices
24/11/2017
Mole translation devices
Extensions - Manual
Used for MQM, MQW, MQY
Single mole, external rotating unit
Measuring a magnet takes about 6 hours
Cable – Automatic
Used for MB 2 moles in parallel.
About 2 hours per magnet.
28/09/2005 J. GARCIA PEREZ
CERN – Geneva – CH
14th International Magnetic Measurement Workshop September 2005, Geneva, Switzerland

7. QIMM Global view 24/11/2017 Coils and mole
VME crate (integrators, ADC, IO, MXI, CPU)
Coils bucking
QIMM measuring a Short Straight Section
SUN workstation
Pneumatic brake
Power Supply
28/09/2005 J. GARCIA PEREZ
CERN – Geneva – CH
14th International Magnetic Measurement Workshop September 2005, Geneva, Switzerland

8. Systems characteristics review
24/11/2017
Systems characteristics review
Characteristic
DIMM
QIMM
Rotating unit placement
internal
external
Number of search coils 3 5
Number of moles built
22 (+3 short) 12
Number of moles per system 2 1
Number of systems built 8
Search coil length [mm]
750
Nominal current [A] 10
12.5
Number of positions measured [750 mm sep.] 20
Search coil surface [m2]
3.7
1.97
Longitudinal positioning
motorized
manual
28/09/2005 J. GARCIA PEREZ
CERN – Geneva – CH
14th International Magnetic Measurement Workshop September 2005, Geneva, Switzerland

9. Measurement and analysis overview
24/11/2017
Measurement and analysis overview
Measurement procedure:
Longitudinal positioning (auxiliary shafts or motor with StegmanTM)
Orientation of mole to gravity
Three Rotating coil measurements clock-wise and 3 anti clock-wise with both positive and negative currents (10 A→B1=7 mT or 12.5 A →B2=3.8 mT)
Discrete Fourier Transform analysis on integrated voltage sampled signals (360 DIMM or 256 for QIMM)
Harmonics normalization with respect to main field and gravity direction
Harmonics normalization to magnetic centre (10th harmonics for dipoles or 1st for quadrupoles) and main field direction
28/09/2005 J. GARCIA PEREZ
CERN – Geneva – CH
14th International Magnetic Measurement Workshop September 2005, Geneva, Switzerland

10. Performance Result DIMM QIMM
24/11/2017
Performance
DIMM & QIMM are very efficient detecting magnet imperfection during CC measurement
Field quality analysis detects misalignments and short circuits
Corrective actions end in decollaring and repair
CM measurement confirms CC one but Field angle measurement validate the magnet
Repeated measurements intended to confirm assembly errors. Faulty measurements below 3 %
Result
DIMM
QIMM
Number of Collared Coil measured
919
314
Number of measurements on Collared Coil
1057
325
Number of Cold Mass measured
850
239
Number of measurements on Cold Mass
Number of magnets with problems found in CC 67 11
Number of magnets with problems found in CM 6
28/09/2005 J. GARCIA PEREZ
CERN – Geneva – CH
14th International Magnetic Measurement Workshop September 2005, Geneva, Switzerland

11. Local and Integrated dipole field
24/11/2017
Local and Integrated dipole field
Local field measurement is very sensitive to assembly errors. Precision better than 10-4
Integrated field → longitudinal positioning precision → StegmannTM encoder precision better than 0.5 mm (Laser Tracker calibration)
Magnetic length adjustment by adding or removing iron yoke laminations
28/09/2005 J. GARCIA PEREZ
CERN – Geneva – CH
14th International Magnetic Measurement Workshop September 2005, Geneva, Switzerland

12. Measuring at the factories: example of assembly error
24/11/2017
Measuring at the factories: example of assembly error
Main Field relative module:
28/09/2005 J. GARCIA PEREZ
CERN – Geneva – CH
14th International Magnetic Measurement Workshop September 2005, Geneva, Switzerland

13. 24/11/2017
High-order Harmonics
Search coils surface matching and their stability keeps precision better than 0.1 units.
28/09/2005 J. GARCIA PEREZ
CERN – Geneva – CH
14th International Magnetic Measurement Workshop September 2005, Geneva, Switzerland

14. Detecting defects – an example
24/11/2017
Detecting defects – an example
Harmonics along the collared coils
28/09/2005 J. GARCIA PEREZ
CERN – Geneva – CH
14th International Magnetic Measurement Workshop September 2005, Geneva, Switzerland

15. 24/11/2017
Field Angle
In dipoles controls the vertical bending component (Tolerance 1 mrad)
Needs good inclinometer (50 μrad) and stability during measurement (apertures parallelism)
To be expressed in the geometrical coordinate system (absolute value)
28/09/2005 J. GARCIA PEREZ
CERN – Geneva – CH
14th International Magnetic Measurement Workshop September 2005, Geneva, Switzerland

16. 24/11/2017
Experience gained
More than half of the production passed. Firm 3 finished already Collared Coils and very soon the Cold Mass.
Feed-back from firms operators very useful to minimize and optimize CERN interventions every 4-5 months. Several maintenance actions are done by firm technicians following our instructions.
Three special, shorter moles (125 mm long search coils) produced to have better spatial resolution to localize defects. One per firm.
DELRINTM feet improve the operation of mole orientation to gravity by its smaller friction coefficient than the originally used metallic feet.
Jig tool to measure angular orientation of the cold mass on the warm magnetic bench is very useful to correct for eventual angular change between geometric and magnetic measurements benches.
Mole calibrations show very good stability of the search coils characteristics and its positioning.
28/09/2005 J. GARCIA PEREZ
CERN – Geneva – CH
14th International Magnetic Measurement Workshop September 2005, Geneva, Switzerland

17. 24/11/2017
Conclusions
Systems show good capability to detect early many defects in the industrial assembly of the LHC dipoles and quadrupoles main magnets
Money savings greater than whole investment in the warm magnetic measurements
System robustness keeps the maintenance frequency low (4-5 months)
Hardware commonly available on the market.
Software developed using industrial control system standards.
Good warm-cold measurements correlation allows a drastic reduction of magnetic measurements test at cold, giving money and time savings
28/09/2005 J. GARCIA PEREZ
CERN – Geneva – CH
14th International Magnetic Measurement Workshop September 2005, Geneva, Switzerland