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J. Garcia-Perez , J. Billan, M. Buzio, P. Galbraith, D. Giloteaux, V. Remondino

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. Introduction Systems Description Measurements and Analysis Overview Performance:

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J. Garcia-Perez , J. Billan, M. Buzio, P. Galbraith, D. Giloteaux, V. Remondino

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  1. Performance of the room temperature Systems for Magnetic Measurements of the LHC Superconducting Magnetsat CERN J. Garcia-Perez, J. Billan, M. Buzio, P. Galbraith, D. Giloteaux, V. Remondino 14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland

  2. Introduction Systems Description Measurements and Analysis Overview Performance: Local and Integrated Dipole Field High-order Harmonics Field Angle Experience Gained Conclusions Outline 14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland

  3. 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 People involved 14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland

  4. The DIMM mole Slip rings Incremental encoder Gravity sensor Rotating coils Pneumatic brake 14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland

  5. 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 14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland

  6. 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. 14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland

  7. QIMM Global view Coils and mole VME crate (integrators, ADC, IO, MXI, CPU) Coils bucking QIMM measuring a Short Straight Section SUN workstation Pneumatic brake Power Supply 14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland

  8. Systems characteristics review 14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland

  9. 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 14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland

  10. 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 % 14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland

  11. 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 14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland

  12. Measuring at the factories: example of assembly error Main Field relative module: 14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland

  13. High-order Harmonics Search coils surface matching and their stability keeps precision better than 0.1 units. 14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland

  14. Detecting defects – an example Harmonics along the collared coils 14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland

  15. 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) 14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland

  16. 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. 14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland

  17. Systems show good capability to detectearlymany 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 Conclusions 14th International Magnetic Measurement Workshop26-29 September 2005, Geneva, Switzerland

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