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Magnetic Measurements of MQW Quadrupoles: Characteristics and Configurations

This document outlines the characteristics and configurations of MQW quadrupoles, detailing two main setups: the defocusing-focusing (DF) and focusing-focusing (FF) configurations. Measurements at various currents (40A, 600A, and 710A) are provided, along with integrated field gradient errors and magnetic center variations. The sensitivity of the MQW quadrupoles to magnetic history is highlighted, revealing discrepancies in magnetic properties across different configurations and sequences. Repeatability of measurements is also discussed, indicating challenges in maintaining consistency.

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Magnetic Measurements of MQW Quadrupoles: Characteristics and Configurations

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  1. Magnetic Measurements: MQW Quadrupoles Didier Cornuet (22/03/2005)

  2. Characteristics of the double aperture quadrupoles MQW Two types of configurations: - Configuration DF (defocusing-focusing): At 40A : Gm = 2,098 T/m Lm = 3,127 m b3 2 units At 710A: Gm = 34,7 T/m Lm = 3,110 m b3 35 units • Configuration FF (focusing-focusing): At 40A : Gm = 2,100 T/m Lm = 3,127 m b3 5,5 units At 600A: Gm = 30,63 T/m Lm = 3,121 m b3 8,0 units

  3. Cross section of the MQW

  4. Principle of measurements - Harmonic analysis - Mole 0,75 m long, displaced in 5 longitudinal positions - No use of the magnet fiducials Magnetic center errors: εx, εy =  0,3 mm Integrated field gradient errors:  2 ‰ @ 40A (Gm.Lm)  1,5 ‰ @ 200A  1 ‰ @ 600A and above Quadrupolar components:  3 units (repeatability) Sextupolar components:  1 unit Other harmonics:  10 %

  5. Problem The MQW quadrupoles are very sensitive to their magnetic history and errors appear to be higher than the expected ones: Δ Gm.Lm of up to 7 ‰ between apertures 1 and 2 @ 40A (DF) Δ b3 of up to 8 units for apertures 1 and 2 @ 40A (DF)

  6. DF configuration FF configuration

  7. Different sequences: 1. DFDMMM DF1 DF2 DM / FFMM FF2 FF1 DM / DFDM - 5 magnets measured with this sequence 3 remeasured and 1 to be remeasured MQW005: - 1 ‰ difference of the Gm.Lm @ 40 A (DF1 checked after FF) - Δb3 = 4 units, although small remanent field measured after demagnetisations (not fully refined)

  8. Different sequences: 2. DFDMMM DF1 DM / FFMM FF1 FF2 DM / DFDM MM DF2 DFDM - 30 magnets measured, where: 4 remeasured 1 to be remeasured 12 magnets: Δ(Gm.Lm) < 2‰ @ 40A 13 magnets: 2‰ < Δ(Gm.Lm) < 3,3‰ @ 40A But we may expect an additional difference of 2‰ to DF1 not measured after FF configuration.

  9. Different sequences: 3. DFDM / FFMM FF1 DM / DFDM MM DF1 DM / FF MM FF2 DM / / DFDMMM DF2 DM - 15 magnets measured, where: MQW030: Δ(Gm.Lm) = 4‰ @ 40A DF1 Δ(Gm.Lm) = 3‰ @ 40A FF1 (demagnetisation procedure not refined) - 2 magnets still to be measured

  10. DF mode @ 40A Aperture 1 Aperture 2 (Gm*Lm) [T] between apertures: b3 [units] :

  11. DF mode @ 710A Aperture 1 Aperture 2 (Gm*Lm) [T] between apertures: b3 [units] :

  12. FF mode @ 40A Aperture 1 Aperture 2 b3 [units] : (Gm*Lm) [T] between apertures:

  13. FF mode @ 600A Aperture 1 Aperture 2 (Gm*Lm) [T] between apertures: b3 [units] :

  14. Measuring Cycle For 710A

  15. Magnetisation Cycle

  16. Old Demagnetisation Cycle - +- +-

  17. Latest Demagnetisation Cycle -+-+-+-

  18. DF 40A

  19. DF 710A

  20. FF 40A

  21. FF 200A

  22. Magnetic center variation in function of the current (DF)

  23. Magnetic center variation in function of the current (FF)

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