Large aperture Q4

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Large aperture Q4M. Segreti, J.M. Rifflet

HiLumi LHC videoconference, 30 August 2012

DSM/IRFU/SACM

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Parameters and specifications

• Within the framework of HiLumi LHC - Task n° 3.5 - Sub-task “Large aperture Q4”, CEA/Saclay is studying the conceptual design of a large aperture two-in-one quadrupole for the outer triplet

• Field quality must be optimized in the domain boundary (1/3 of aperture radius) with consideration of cross-talk due to double aperture

• Nominal gradient could be low and compensated by magnetic length: value of [Nominal gradient × Magnetic length] can be the same than that of actual MQY magnet, i.e. 160 T/m × 3.4 m = 544 T

• Margin to quench must be at least 20% at nominal current

• CERN firstly proposed as a first approach to use MQM (2 layers) or MQ (1 layer) cable and afterwards to add studies using only one layer of MQM cable

• For all studies, cable insulation and inter-pole insulation thicknesses were assumed to be the same than those of actual MQM or MQ magnets

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Parameters Actual MQY Large aperture Q4 Observation for large aperture Q4

kind of magnet Cos-tetha Cos-tetha Preferably

Technologie NbTi NbTi Preferably

Aperture separation Double-aperture Double-aperture 194 mm spaced (like LHC MQ or actual MQY)

Coil inner diameter 70 mm 85 - 90 - 100 mm or more As large as possible

Kind of cable MQY inner-outer (4 layers) MQM (2 layers) or MQ (1 layer) As a first approach

Margin 18% 20% At least

Operating Temp. 4.5 K 1.9 K As a first approach. Then see option at 4.5 K

Magnetic length 3.4 m up to 6 m Space available for increasing the length

Nominal gradient 160 T/m Can be low but compensated by length

Nominal current 3610 A Depends of cable

Quench voltage 700 V Seems to be realistic

Hot spot criterion 200 K Max. Seems to be realistic

Kind of cables Width (mm) Min thick (mm) Max thick (mm) Nb strands Transp (mm) Degrad (%) Fil

MQY inner 8.3 1.15 1.40 22 66 5 NbTi

MQY outer 8.3 0.78 0.91 34 66 5 NbTi

MQM 8.8 0.78 0.91 36 66 5 NbTi

MQ 15.1 1.362 1.598 36 100 5 NbTi

Strand Diam (mm) Cu/sc RRR Tr (K) Br (T) Jc @ BrTr dJc/dBMQY inner 0.735 1.25 80 4.5 5 2670 600MQY outer et MQM 0.48 1.75 80 1.9 5 2800 600MQ 0.825 1.9 80 1.9 9 2246 550

Parameters and specifications

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Optimized solutions (ROXIE) with 2 layers of MQM cable

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Aperture (mm)

Current (A)

Gradient(T/m)

Magn. Length(m) Field harmonics (normal relative multipoles × 10-4) Coil azim. stress

(Mpa)b1 b3 b4 b5 b6 b10 b14 b18 Peak Average

85 4945 135 4.03 -1.59 -0.01 0.15 -0.11 0.00 0.00 1.22 -0.65 132 6890 4865 128 4.25 -3.12 0.29 0.20 -0.38 0.00 0.00 1.15 -0.67 121 6795 4877 121 4.50 -7.92 0.44 0.25 -0.95 0.00 0.00 1.17 -0.67 135 69

100 4718 116 4.69 -26.66 -1.18 0.58 -2.26 0.00 0.00 1.51 -0.75 113 65

3.80

4.00

4.20

4.40

4.60

4.80

115

120

125

130

135

140

85 90 95 100

Mag

netic

leng

th (m

)

Gra

dien

t (T/

m)

Aperture Ø (mm)

Gradient

Magn. length

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

85 90 95 100

Nor

mal

rela

tive

mul

tipol

es (×

10-4

)

Aperture Ø (mm)

b3

b4

b5

b14

b18

Here is considered the same nominal current in left and right apertures of each double-aperture

• Higher is the aperture, lower is the gradient with 20 % margin to quench

• Gradient could be compensated by magnetic length

• b1 is high for all apertures but corresponds to an off-centering of only a few tenths of millimeters

• b3, b4 and b5 become high from 100 mm aperture

Optimized solutions (ROXIE) with 2 layers of MQM cable

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Optimized solutions (ROXIE) with 1 layer of MQ cable

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Aperture (mm)

Current (A)

Gradient(T/m)



85 16602 125 4.35 -2.85 -0.31 0.20 -0.04 0.00 0.00 2.07 0.19 99 6390 16188 120 4.53 -9.21 -1.01 0.22 -0.17 0.00 0.00 2.23 0.06 101 6495 15485 113 4.81 -22.59 -2.67 0.25 -0.47 0.00 0.00 2.47 -0.36 102 64

100 15199 108 5.04 -48.57 -5.39 0.36 -1.44 0.00 0.00 1.99 -0.40 104 66




• b1 is high for all apertures but corresponds to a dis-centering of only a few tenths of millimeters

• b3 becomes high from 95 mm aperture and b5 from 100 mm aperture

Optimized solutions (ROXIE) with 1 layer of MQ cable

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Optimized solutions (ROXIE) with only 1 layer of MQM cable

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Aperture (mm)

Current (A)

Gradient(T/m)



85 7124 108 5.04 -0.34 -0.05 0.22 0.00 0.00 0.00 1.22 -0.59 92 6090 7043 102 5.33 -0.44 -0.05 0.23 -0.01 0.00 0.00 2.19 -0.59 88 6195 6908 95 5.73 -0.46 -0.05 0.24 -0.02 0.00 0.00 2.72 -0.58 88 61

100 6900 91 5.98 -0.35 0.02 0.25 -0.04 0.00 0.00 3.39 -0.49 89 62105 6767 85 6.40 -0.51 0.05 0.28 -0.13 0.00 0.00 3.72 -0.48 89 62110 6758 82 6.63 -1.98 0.02 0.33 -0.38 0.00 0.00 3.93 -0.30 93 63115 6656 77 7.06 -3.90 0.30 0.41 -0.99 0.00 0.00 4.02 -0.32 94 63120 6626 75 7.25 -7.08 1.45 0.57 -2.73 0.00 0.00 4.03 -0.14 96 64




• b1 is high for all apertures but corresponds to an off-centering of only a few tenths of millimeters

• b3, b4 and b5 become high from 120 mm aperture

4.00

4.40

4.80

5.20

5.60

6.00

6.40

6.80

7.20

70

80

90

100

110

120

130

140

85 90 95 100 105 110 115 120

Mag

netic

leng

th (m

)

Gra

dien

t (T/

m)

Aperture Ø (mm)

Gradient

Mag length

-5.5

-4.5

-3.5

-2.5

-1.5

-0.5

0.5

1.5

2.5

3.5

4.5

85 90 95 100 105 110 115 120

Nor

mal

rela

tive

mul

tipol

es (×

10-4

)

Aperture Ø (mm)

b3

b4

b5

b14

b18

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A C

B

D

O

Back collar keyway

Collars mid-plane

q

Perfect contact between layers is assumed

Front collar

Mechanical computation

• Due to symmetries, the 2D CASTEM model is restricted to one octant

• 2 levels of collars to simulate effect of stacking in alternated layers

• Boundary conditions imposed at symmetry planes

Thermo-mechanical propertiesMaterials Temp. Elastic Yield Ultimate Integrated

Componants Modulus Strength Strength Thermal Shrinkage(K) E (GPa) (MPa) (MPa) a (mm/m)

yus 130 S Nippon Steel 300 190 445 795Collars 2 210 1023 1595 2.4

316L Stainless Steel 300 205 275 596Keys 2 210 666 1570 2.9

Copper 300 136Angular wedges 2 136 3.3Kapton Foils 300 2.5

inter-layer & inter-pole insulations 2 4 6.0 insulated NbTi conductor blocks 300 7.50 *

Coils with MQM cable 2 11.25 * 5.0 * insulated NbTi conductor blocks 300 10.00

Coils with MQ cable 2 15.00 4.9* For MQM insulated conductor, it is assumed that: E 2K = 1.5 × E 300K and a = 5.0 mm/m (see in red)

In this example is presented the 90 mm aperture design using 2 layers of MQM cable

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Collaring, relaxation due to insulation creep, cool-down and energization are simulated with the CASTEM software package:

• The collaring process is simulated by prescribing an azimuthal gap between the sides of the keys and collar keyways (gap angle θ)

• The relaxation due to insulation creep is in first assumed to be 20 %. Creep is modeled by a 20 % reduction of the gap angle θ which is maintained for the next steps (cooling and energization)

• The cooling is modeled by an applied thermal body force over the entire structure (by the use of integrated thermal shrinkages of each material from 300 K to 2 K)

• The magnetic forces induced at nominal current are computed at each coil node using the magneto-static module of CASTEM software package


A C

B

D

O

Back collar keyway

Collars mid-plane

q

Perfect contact between layers is assumed

Front collar

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For each magnetic design, mechanical study allowed to verify that the following objectives were reached:

• all parts of coils remained in compression at nominal current with a security margin of 10 MPa to avoid any separation on polar plan between coils and collars, see Fig. on top

• during all phases, peak stress in coils was below 150 MPa (arbitrary, but reasonable value) to avoid any possible degradation of the cable insulation, see table below

• coil radial displacement due to magnetic forces during excitation was low (below 50 µm), see Fig. below

MPa

Q4_Opti90mm Collaring Creep (20%) Cool down EnergizationAzimuthal stress in coil (MPa)Max -121 -97 -97 -90Average -67 -53 -46 -47Min on polar plane

-10

Average on polar plane -15Coil radial displacement due to Lorentz forces (µm)Point A

33Point B 10Point C 19Point D 2Max von Mises stress (MPa)In collars 927 741 704 823In keys 323 258 257 289

µm

A

B

C

D


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Effect of cross-talk in unbalanced regime

Here is now considered a 20 % and 50% unbalanced regimes in the case of designs using 2 layers of MQM cable:

• Left aperture is at nominal current• Right aperture is at 20 % or 50% lower current

20% unbalanced regime 50% unbalanced regimeØ aper Current(mm) (A) b1 b3 b4 b5 b6 b7 b10 b14 b18

85 4945 21.58 3.31 -0.23 0.87 -0.45 0.09 0.00 1.25 -0.6690 4865 22.07 3.18 -0.52 1.06 -0.62 0.12 0.00 1.17 -0.6895 4877 1.85 10.45 0.16 2.24 -0.82 0.23 0.00 1.19 -0.68

100 4718 -29.67 30.98 3.26 5.17 -1.25 0.43 0.00 1.56 -0.78

Ø aper Current(mm) (A) b1 b3 b4 b5 b6 b7 b10 b14 b18

85 3956 -101.76 -13.71 2.07 -1.58 -0.22 -0.13 0.00 1.22 -0.6490 3892 -112.56 -16.18 2.54 -2.02 -0.31 -0.18 0.00 1.14 -0.6695 3902 -98.15 -28.09 4.39 -3.76 -0.40 -0.33 0.00 1.16 -0.66

100 3774 -74.84 -57.35 9.60 -7.74 -0.68 -0.60 0.00 1.51 -0.76

Normal relative multipoles (× 10-4) in the left aperture

Normal relative multipoles (× 10-4) in the right aperture


85 4945 56.06 15.87 2.24 2.46 -0.60 0.10 0.00 1.29 -0.6890 4865 20.92 21.96 3.77 3.65 -0.74 0.14 0.00 1.22 -0.7195 4877 24.56 24.99 3.99 4.49 -0.97 0.17 0.00 1.24 -0.71

100 4718 73.84 18.95 1.34 4.22 -1.60 0.23 0.00 1.60 -0.80


85 2473 -405.14 -68.25 13.59 -6.67 0.17 -0.23 0.00 1.21 -0.6490 2433 -381.53 -90.27 19.75 -9.78 0.38 -0.40 0.00 1.14 -0.6695 2439 -427.30 -107.71 24.12 -12.47 0.57 -0.53 0.00 1.15 -0.66

100 2359 -564.98 -110.92 24.27 -13.37 0.32 -0.73 0.00 1.47 -0.73



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Here is considered a 20 % and 50% unbalanced regimes in the case of designs using 1 layer of MQ cable:


20% unbalanced regime 50% unbalanced regime

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85 16602 34.11 21.08 3.67 2.79 -0.28 0.06 0.00 2.18 0.2090 16188 24.30 25.46 4.50 3.69 -0.37 0.09 0.00 2.36 0.0695 15485 77.04 19.30 2.29 3.27 -0.56 0.10 0.01 2.61 -0.38

100 15199 31.44 30.56 4.89 5.38 -0.56 0.16 0.01 2.12 -0.42


85 8301 -335.10 -74.51 15.37 -7.12 0.39 -0.19 0.00 2.06 0.1990 8094 -354.54 -92.26 19.90 -9.59 0.59 -0.30 0.00 2.22 0.0695 7743 -490.22 -91.43 19.35 -9.80 0.62 -0.37 0.00 2.44 -0.35

100 7600 -451.35 -126.50 29.06 -15.15 1.20 -0.58 0.00 1.98 -0.39




85 16602 22.87 4.13 0.22 0.85 -0.20 0.07 0.00 2.11 0.2090 16188 23.54 4.10 -0.01 1.05 -0.27 0.10 0.00 2.27 0.0695 15485 24.41 4.12 -0.27 1.27 -0.28 0.14 0.01 2.52 -0.36

100 15199 -6.99 17.01 1.31 3.34 -0.37 0.30 0.01 2.05 -0.41


85 13282 -95.65 -13.72 2.37 -1.50 -0.01 -0.10 0.00 2.06 0.1990 12950 -105.83 -16.07 2.84 -1.95 0.00 -0.16 0.00 2.22 0.0695 12388 -117.02 -18.98 3.47 -2.48 0.08 -0.22 0.00 2.45 -0.36

100 12159 -90.46 -38.24 6.63 -5.36 0.11 -0.44 0.00 1.99 -0.40



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Here is considered a 20 % and 50% unbalanced regimes in the case of designs using only one layer of MQM cable:


20% unbalanced regime 50% unbalanced regime

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85 7124 20.97 5.76 0.72 0.98 -0.23 0.06 0.00 1.25 -0.6090 7043 23.68 6.51 0.74 1.29 -0.32 0.10 0.01 2.24 -0.6095 6908 10.26 9.93 1.45 2.14 -0.37 0.18 0.01 2.80 -0.60

100 6900 1.78 12.92 1.88 3.11 -0.55 0.30 0.01 3.50 -0.50105 6767 8.05 12.63 1.52 3.47 -0.72 0.37 0.02 3.84 -0.49110 6758 10.40 13.53 1.21 3.98 -1.04 0.46 0.02 4.06 -0.31115 6656 -10.09 24.95 3.29 6.76 -1.33 0.70 0.02 4.19 -0.33120 6626 -14.38 37.31 4.45 10.14 -2.60 1.14 0.02 4.21 -0.14


85 5699 -77.16 -13.62 2.48 -1.54 -0.06 -0.09 0.00 1.22 -0.5990 5634 -88.20 -16.44 3.10 -2.07 -0.09 -0.14 0.00 2.18 -0.5895 5526 -80.49 -22.94 4.72 -3.32 -0.05 -0.26 0.01 2.72 -0.58

100 5520 -79.56 -29.38 6.20 -4.79 -0.11 -0.42 0.01 3.39 -0.49105 5414 -97.05 -32.32 6.96 -5.58 -0.14 -0.53 0.01 3.72 -0.48110 5406 -110.74 -37.37 8.09 -6.68 -0.28 -0.68 0.01 3.92 -0.30115 5325 -98.29 -55.95 12.48 -10.68 -0.32 -1.02 0.01 4.04 -0.32120 5301 -105.32 -76.11 16.09 -15.51 -1.18 -1.63 0.01 4.05 -0.14




85 7124 57.39 19.75 3.66 2.53 -0.40 0.01 0.01 1.29 -0.6290 7043 59.02 22.74 4.54 3.52 -0.47 0.05 0.01 2.33 -0.6295 6908 65.21 25.70 4.81 4.13 -0.60 0.10 0.01 2.91 -0.63

100 6900 66.36 28.11 5.51 5.37 -0.79 0.17 0.01 3.64 -0.52105 6767 70.90 30.42 5.66 6.18 -0.99 0.22 0.02 4.02 -0.51110 6758 42.10 38.13 8.02 8.93 -1.10 0.37 0.02 4.27 -0.32115 6656 29.43 44.73 9.58 11.05 -1.40 0.42 0.01 4.41 -0.35120 6626 21.51 54.92 11.71 14.74 -2.68 0.65 0.02 4.45 -0.15


85 3562 -312.76 -63.27 13.26 -6.14 0.13 -0.07 0.00 1.21 -0.5890 3522 -346.08 -76.24 17.19 -8.58 0.33 -0.18 0.00 2.17 -0.5895 3454 -390.11 -90.63 20.63 -10.51 0.49 -0.32 0.00 2.69 -0.58

100 3450 -427.97 -105.89 25.64 -13.88 0.75 -0.54 0.01 3.35 -0.48105 3384 -474.45 -122.94 30.61 -16.77 1.09 -0.73 0.01 3.67 -0.47110 3379 -466.10 -152.88 40.90 -23.71 1.91 -1.17 -0.02 3.89 -0.29115 3328 -489.90 -183.29 51.04 -30.00 2.54 -1.49 -0.04 3.99 -0.32120 3313 -522.07 -221.92 63.39 -39.57 2.81 -2.20 -0.04 3.99 -0.14



In every cases, b1, b3, b4 and b5 are impacted (b1 and b3 highly) by cross-talk due to unbalanced

regime, especially in the right aperture where the current is lower What is acceptable?

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What obtain we with a 20 % and 50% unbalanced regimes in the case of the actual 70 mm aperture MQY magnet?

• Left aperture is at nominal current (3600 A)• Right aperture is at 20 % (2880 A) or 50%

(1800 A) lower current

unbalanced Currentregime (%) (A) b1 b3 b4 b5 b6 b7 b10 b14 b18

0 3600 16.47 0.48 0.12 0.30 5.40 0.01 -5.00 1.12 -0.1720 3600 18.47 7.25 0.13 0.72 5.32 0.03 -5.10 1.14 -0.1750 3600 67.22 9.82 0.69 0.92 5.37 0.02 -5.22 1.17 -0.17

unbalanced Currentregime (%) (A) b1 b3 b4 b5 b6 b7 b10 b14 b18

0 3600 -16.47 -0.48 0.12 -0.30 5.40 -0.01 -5.00 1.12 -0.1720 2880 -124.10 -17.83 1.97 -1.22 5.34 -0.05 -5.00 1.12 -0.1750 1800 -527.80 -53.88 8.49 -3.06 5.48 -0.07 -4.94 1.11 -0.17



b1, b3, b4 and b5 are also impacted (b1 and b3 highly) by cross-talk due to unbalanced regime, especially in the right aperture where the current is lower.

Yet this magnet is working well actually

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Conclusions

• Optimized magnetic designs for the large aperture Q4 have been presented with MQM (2 layers) and MQ (1 layer) cable with 85, 90, 95 and 100 mm apertures

• To try to reduce the cross-talk effect due to unbalanced regime (by increasing the iron mass), magnetic designs with only one layer of MQM cable were studied with 85, 90, 95, 100, 105, 110, 115 and 120 mm apertures. Finally, results on harmonics are at the same order than those obtained with the two previous kinds of configuration (2 layers of MQM and 1 layer of MQ cable)

• Mechanical simulations of each main phase (collaring, relaxation due to creep, cooling and energization) have been realized and have validated the collaring process for all the magnetic designs

• In case of unbalanced regime, some normal relative multipoles become very high, especially in the aperture where the current is 20% or 50% lower. This is also verified with ROXIE simulations using the actual 70 mm aperture MQY magnet design which is well working yet in the LHC machine

• In case of unbalanced regime, what is finally acceptable for harmonics?

• Which magnetic design(s) can be chosen as baseline for the Q4 magnet (don’t forget the high needed magnetic length of some designs to compensate their low gradient)?

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