1. Ranko Ostojic AT/MEL 1.Beam heat loads 2.Magnet design issues related to heat loads

2. Insertion Magnets and Beam Heat Loads R. Ostojic, AT/MEL 2 LHC experimental insertions Dispersion suppressor Matching sectionSeparation dipoles Final focus P/L (W/m) pp collisions at 7 TeV generate 900 W at L nom carried by the secondaries to each side of LHC experimental insertion.

3. Insertion Magnets and Beam Heat Loads R. Ostojic, AT/MEL 3 Heat load in the Low- Triplet Average load:7 W/m Peak: 14 W/m Total: 205 W T. Peterson, FNAL Technical Note July 2002 External Heat Exchanger

4. Insertion Magnets and Beam Heat Loads R. Ostojic, AT/MEL 4 Heat load in the Low- Triplet N. Mokhov et al, LHC Project Report 633 Peak power density: 0.45 mW/g

5. Insertion Magnets and Beam Heat Loads R. Ostojic, AT/MEL 5 MQXA low- quadrupole (KEK) Coil ID70 mm G = 215 T/m at 1.9 K Conductors 1/2 Width11/11 mm Mid-thick1.48/1.34 mm Strand dia0.815/0.735 mm No strands27/30

6. Insertion Magnets and Beam Heat Loads R. Ostojic, AT/MEL 6 MQXA Heat Transfer Experiments (I) Exp Conductor Strand materialCu-Ni Strand dia0.814 mm No strands27 Cross-section1.47 x 11 mm Length177 mm Insulation Upilex15 mm/25  m pitch50% overlap + Upilex 6 mm/50  m B-stage epoxy 10  m pitch 8 mm (2 mm gap) N. Kimura et al, IEEE Trans. Appl. Superconductivity, Vol 9, No 2, (1999) p 1097.

7. Insertion Magnets and Beam Heat Loads R. Ostojic, AT/MEL 7 MQXA Heat Transfer Experiments (II)

8. Insertion Magnets and Beam Heat Loads R. Ostojic, AT/MEL 8 MQXA Heat Transfer Experiments (III) Conclusions: -effective channel diameter ~ 35 m -Conduction important at higher heat flux -AC loss measurements give consistent results -Maximum allowed heat load ~ 18 mW/cm3

9. Insertion Magnets and Beam Heat Loads R. Ostojic, AT/MEL 9 MQXB low- quadrupole (FNAL) Coil ID70 mm G = 215 T/m at 1.9 K Conductors 1/2 Width15.4/15.4 mm Mid-thick1.45/1.14 mm Strand dia0.808/0.650 mm No strands37/46

10. Insertion Magnets and Beam Heat Loads R. Ostojic, AT/MEL 10 MQXB Heat Transfer Experiments (I) Insulation 1 st coil layer Polyimide 9.5 mm/25 m pitch 55% overlap + Polyimide 9.5 mm/50 m QXI pitch 11.5 (2 mm gap) 2 nd coil layer Polyimide 9.5 mm/25 m pitch 43% overlap Polyimide 9.5 mm/25 m QXI pitch 50% overlap L. Chiesa et al, IEEE Trans. Appl. Superconductivity, Vol 11, No 1, (2001) p 1625.

11. Insertion Magnets and Beam Heat Loads R. Ostojic, AT/MEL 11 MQXB Heat Transfer Experiments (II) Conclusions: -AC loss results consistent with assumption of “blocked cooling channels” -Maximum allowed heat load ~ 1.6 mW/g

12. Insertion Magnets and Beam Heat Loads R. Ostojic, AT/MEL 12 MQM matching quadrupole Coil ID 56 mm Gradient 200 T/m at 1.9 K 160 T/m at 4.5 K Conductor Width8.8 mm Strand dia0.480 mm No strands36 Insulation Polyimide 8 mm/25  m pitch 50% overlap + Polyimide 9 mm/50  m unc. poly. 6  m pitch 11 mm (2 mm gap)

13. Insertion Magnets and Beam Heat Loads R. Ostojic, AT/MEL 13 MQY wide aperture quadrupole Coil ID 70 mm Gradient 160 T/m at 4.5 K Conductor 1/2 Width8.3 mm Strand dia0.48/0.73 mm No strands34/22 Insulation Polyimide 8 mm/25  m pitch 50% overlap + Polyimide 9 mm/50  m unc. poly. 7  m pitch 11 mm (2 mm gap)

14. Insertion Magnets and Beam Heat Loads R. Ostojic, AT/MEL 14 Separation dipoles (BNL) Coil ID 80 mm Field 3.8 T at 4.5 K (2.4 T at 4.5 K in IR1/5) Conductor Width9.73 mm Strand dia0.648 mm No strands30 Insulation Kapton CI 9 mm wide 50  m thick pitch 50% overlap + Kapton CI 9 mm 50  m pitch 50% overlap

15. Insertion Magnets and Beam Heat Loads R. Ostojic, AT/MEL 15 MQTL Coil ID 56 mm Gradient 120 T/m at 1.9 K 90 T/m at 4.5 K SC wire 0.73 mm x 1.25 mm (with enamel insulation) Coil Insulation epoxy impregnated

16. Insertion Magnets and Beam Heat Loads R. Ostojic, AT/MEL 16 Heat transfer in Saturated He Bath Y. Iwamoto et al, IEEE Trans. Appl. Superconductivity, Vol 14, No 2, (2004) p 592. Quench Stability Study of J-PARC Magnets Cable and insulation identical to MQXA 20 mJ/cm3 in a 10 ms pulse

17. Insertion Magnets and Beam Heat Loads R. Ostojic, AT/MEL 17 Summary of expected quench limits

18. Insertion Magnets and Beam Heat Loads R. Ostojic, AT/MEL 18 Possible experiments on production magnets QH L4 QH L2-3 MQY in B4: -Use one QH L2-3 for coil heating -Magnet protection by QHL4 MQM and MQY in SM18: -Use anti-cryostat heaters to verify operating margins at 4.5 K

19. Insertion Magnets and Beam Heat Loads R. Ostojic, AT/MEL 19 Conclusions Heat loads associated to pp collisions are considerable in the experimental insertions, in particular in the low-beta triplets. Thermal properties of the coils of both types of low-beta quadrupoles were experimentally studied, and confirm a safety factor of 3 with respect to expected heat load for nominal luminosity. MQM and MQY quadrupoles have insulation schemes analogous to the MB. Similar thermal properties could be expected, but have not been experimentally verified. Magnets operating at 4.5 K are expected to have higher quench limits for transient losses, but lower for continuous losses than at 1.9K.