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Magnetic Measurements: MQW Quadrupoles

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

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Magnetic Measurements: MQW Quadrupoles

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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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