Download - Insertion Magnets and Beam Heat Loads
Ranko Ostojic
AT/MEL
1. Beam heat loads
2. Magnet design issues related to heat loads
Insertion Magnets and Beam Heat Loads
R. Ostojic, AT/MEL 2
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LHC experimental insertions
Dispersion suppressor Matching section Separation dipoles
Final focus
P/L (W/m)pp collisions at 7 TeV generate 900 W at Lnom
carried by the secondaries to each side of LHC experimental insertion.
Insertion Magnets and Beam Heat Loads
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Heat load in the Low- Triplet
Average load: 7 W/mPeak: 14 W/mTotal: 205 W
Total integrated heat load to inner triplet = 205.5 Watts
<---Q1 quad---> <----Q3 quad----> <--------------Q2 quad--------------->
Heat Load in Inner Triplet Quads versus Position
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Heat "bin" (blue are 0.55 m long, red about 1 m long)
He
at
to 1
.9 K
(W
/m)
T. Peterson, FNAL Technical Note July 2002
External Heat Exchanger
Insertion Magnets and Beam Heat Loads
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Heat load in the Low- Triplet
N. Mokhov et al, LHC Project Report 633Peak power density:
0.45 mW/g
Insertion Magnets and Beam Heat Loads
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MQXA low- quadrupole (KEK)
Coil ID 70 mmG = 215 T/m at 1.9 K
Conductors 1/2 Width 11/11 mm Mid-thick 1.48/1.34 mm Strand dia 0.815/0.735 mm No strands 27/30
Insertion Magnets and Beam Heat Loads
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MQXA Heat Transfer Experiments (I)
Exp ConductorStrand material Cu-NiStrand dia 0.814 mmNo strands 27Cross-section 1.47 x 11 mmLength 177 mm
InsulationUpilex 15 mm/25 mpitch 50% overlap
+Upilex 6 mm/50 mB-stage epoxy 10 mpitch 8 mm (2 mm
gap)
N. Kimura et al, IEEE Trans. Appl. Superconductivity, Vol 9, No 2, (1999) p 1097.
Insertion Magnets and Beam Heat Loads
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MQXA Heat Transfer Experiments (II)
Insertion Magnets and Beam Heat Loads
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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
Insertion Magnets and Beam Heat Loads
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MQXB low- quadrupole (FNAL)
Coil ID 70 mmG = 215 T/m at 1.9 K
Conductors 1/2 Width 15.4/15.4 mm Mid-thick 1.45/1.14 mm Strand dia 0.808/0.650 mm No strands 37/46
Insertion Magnets and Beam Heat Loads
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MQXB Heat Transfer Experiments (I)
Insulation1st coil layer
Polyimide 9.5 mm/25 mpitch 55% overlap
+Polyimide 9.5 mm/50 mQXIpitch 11.5 (2 mm
gap)
2nd coil layerPolyimide 9.5 mm/25 mpitch 43% overlapPolyimide 9.5 mm/25 mQXIpitch 50% overlap
L. Chiesa et al, IEEE Trans. Appl. Superconductivity, Vol 11, No 1, (2001) p 1625.
Insertion Magnets and Beam Heat Loads
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MQXB Heat Transfer Experiments (II)
Conclusions:-AC loss results consistent with assumption of “blocked cooling channels”-Maximum allowed heat load ~ 1.6 mW/g
Insertion Magnets and Beam Heat Loads
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MQM matching quadrupole
Coil ID 56 mmGradient 200 T/m at 1.9 K
160 T/m at 4.5 K
ConductorWidth 8.8 mmStrand dia 0.480 mmNo strands 36
InsulationPolyimide 8 mm/25 mpitch 50% overlap
+Polyimide 9 mm/50 munc. poly. 6 mpitch 11 mm (2 mm
gap)
Insertion Magnets and Beam Heat Loads
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MQY wide aperture quadrupole
Coil ID 70 mmGradient 160 T/m at 4.5 K
Conductor 1/2Width 8.3 mmStrand dia 0.48/0.73 mmNo strands 34/22
InsulationPolyimide 8 mm/25 mpitch 50% overlap
+Polyimide 9 mm/50 munc. poly. 7 mpitch 11 mm (2 mm
gap)
Insertion Magnets and Beam Heat Loads
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Separation dipoles (BNL)
Coil ID 80 mmField 3.8 T at 4.5 K
(2.4 T at 4.5 K in IR1/5)
ConductorWidth 9.73 mmStrand dia 0.648 mmNo strands 30
InsulationKapton CI 9 mm wide
50 m thickpitch 50% overlap
+Kapton CI 9 mm
50 mpitch 50% overlap
Insertion Magnets and Beam Heat Loads
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MQTL
Coil ID 56 mmGradient 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 Insulationepoxy impregnated
Insertion Magnets and Beam Heat Loads
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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
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Summary of expected quench limits
Magnet Coil insulationOperating
temperatureConditions/Reference
Temperature margin
Heat reserve (transient losses)
Peak power density
Temperature margin
Heat reserve (transient losses)
Peak power density
MB 2x50mu (50% overlap) + 73 mu (2 mm gap) 1.9 K 7 K 38 mJ/cm3 10 mW/cm3 1 K 0.8 mJ/cm3 5 mW/cm3 LPR 44; Meuris et al. (1999)MQXA 2x25mu (50% overlap) + 60 mu (2 mm gap) 1.9 K 8.2 K 55 mJ/cm3 1.3 K 1.3 mJ/cm3 4 mW/cm3 Kimura et al, IEEE Tran SC., 9(1999)1097MQXB 2x25mu (55% overlap) + 50 mu (2 mm gap) 1.9 K 8 K 50 mJ/cm3 1.2 K 1.2 mJ/cm3 0.4 mW/g Mohkov et al., LPR 633MQM 2x25mu (50% overlap) + 55 mu (2 mm gap) 1.9 K 7.5 K 50 mJ/cm3 10 mW/cm3 1 K 1.0 mJ/cm3 5 mW/cm3MQM 2x25mu (50% overlap) + 55 mu (2 mm gap) 4.5 K 6.5 K 75 mJ/cm3 1.2 K 5 mJ/cm3 2 mW/cm3MQY 2x25mu (50% overlap) +55 mu (2 mm gap) 4.5 K 6.5 K 75 mJ/cm3 1.4 K 5 mJ/cm3 2 mW/cm3MQTL B-stage epoxy impregnated 4.5 K 6.5 K 75 mJ/cm3 2 K 5 mJ/cm3 1.0 mW/cm3 R.Wolf, Pr comm., 28 July 2004
Injection Collision
Insertion Magnets and Beam Heat Loads
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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
Insertion Magnets and Beam Heat Loads
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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.