Quadrupole design study for the lhc phase I upgrade (3 rd iteration)

F.Borgnolutti

Quadrupole design study for the lhc phase I upgrade

(3rd iteration)

F. BorgnoluttiMagnets, Cryostats and Superconductors Group

Accelerator Technology Department, CERN

CERN, 24th July 2008

Acknowledgments:E. Todesco, P. Fessia

24th July 2008-Quadrupole design study for the LHC phase I upgradeF.Borgnolutti

content

Summarized of the previous workStudy of the dimension and location of the holes in the iron yoke for the He flowConclusion IPreliminarily designs for a possible second cables distributionConclusion II & Future work


SUMMARIZED OF THE PREVIOUS WORK


Summarized of the previous work

We optimized quads with apertures of 110, 120 and 130mm2 layers, 3 and 4 blocks designs are considered

The cable performances are derived from the latest measurements performed at 1.9K on the spare cables of the LHC main dipole:

Cable 01 (inner layer): 14800 A @ 10T (slope of 4680 A/T)Cable 02 (outer layer): 14650 A @ 9T (slope of 4050 A/T)


An analytical study showed that the short sample gradient we can expect (without iron yoke) is of:

138 T/m for the 130mm aperture148 T/m for the 120mm aperture157 T/m for the 110mm aperture

An iron yoke placed at 37mm from the coil increases the short sample gradient by ~3-5%Special grading


does not dramatically increase the short sample gradientUses more cable 01 which is the shorter cable length

Unit length of cable 01: 460 mUnit length of cable 02: 780 m



Constrains: Field quality

Multipoles b6, b10 and b14 < 1 unit (at Rref = 2/3 of the aperture radius)

MechanicalMinimal angular thickness of the Pole nose of

8.5º for the 110mm7.7º for the 120mm7.0º for the 130mm

Insulation at the mid-plane2 common sheet of 0.12mm2 additional sheet of 0.1mm at the outer layer

Inter-layer thickness of 0.5mmThickness of the copper wedge nose > 1 mm

too small (to avoid cutting the insulation)

S=16mm

nose


First set of designs (without iron):

110mm (MQXC V13)

nb turn short sample Gmax

magnet cable 01 cable 02 G (T/m) I (A) Bp (T) b6 b10 b14 expected

110 mm MQXC V13 15 19 154 16330 8.6 0.70 0.34 0.76 157

120mm MQXC V3 18 19 145 16860 9.6 -0.5 0.32 1.23 148

MQXC V8 18 17 144 17110 9.5 -0.06 0.04 -0.71

130 mm MQXC V2 23 20 136 16290 9.7 -0.42 0.16 -0.70 138

120mm (MQXC V3) 120mm (MQXC V8)


130mm (MQXC V2)


STUDY OF THE DIMENSION AND LOCATION OF THE HOLES IN THE IRON YOKE FOR THE He FLOW


IRON yoke geometry

Iron yoke dimensionsIn all cases the collar thickness is of 37mm and the outer radius of the yoke is set at 275mm. Therefore the yoke thickness depends on the aperture diameter:

110mm aperture yoke thickness of 152mm120mm aperture “ 147mm130mm aperture “ 142mm

Possible holes dimensions an positions in the yoke for He flowHoles of 80mm

4 holes located at the mid-planes

4 holes located at thepoles

It’s possible to move a bit the holes radialy while keeping at least 16mm of matter


IRON yoke geometry

Holes of 110mm4 holes located at the mid-planes4 holes located at the polesThe holes have to be centered in the yoke

Aperture of 110mm d=21mm (d=36mm for 80mm hole)

Aperture of 120mm d=18.5mm(d=33.5 for 80mm hole)

Aperture of 130mm d=16mm(d=31 for 80mm hole)

110 mmd37 mm

275

mm


Iron yoke effect on magnetic field

Influence of the holes dimensions and positions in the iron yoke on the magnetic field: We study the 120mm MQXC V8 case

For the 80mm cases the reduction of the transfer function is of 1-1.5%, it is ~1% higher for the 110mm cases.In all cases, the reduction of the transfer function is in between what we have for the MQXB (2%) and MQXA (5.2%)

TF Holes diameter of 80mm

98

98.5

99

99.5

100

100.5

0 5000 10000 15000I (A)

(B2/

I)/(

B20

/I0)

(%)

4 holes 45º, rsd center of 202mm

4 holes 45º, rad center of 202-5mm

4 holes 45º, rad center of 202+5mm


4 holes 0º, centered

4 holes 0º, centred+10mm

TF Holes diameter of 110mm

97

97.5

98

98.5

99

99.5

100

100.5

0 5000 10000 15000I (A)

B2/

I 4 holes at 45º

4 holes at 0º


Iron yoke effect on magnetic field

b6Holes diameter of 80mm

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

0 2000 4000 6000 8000 10000 12000 14000 16000

I (A)

b6

(un

it)

4 holes 45º, rsd center of 202mm

4 holes 45º, rad center of 202-5mm

4 holes 45º, rad center 202+5mm


4 holes 45º, 110mm centered

4 hole 0º, centered

4 holes 0º, centered+10mm

Multipoles versus current

Δb6 is a bit smaller when the holes are located at the mid-plane

In both the 80mm and 110mm hole diameters cases, the Δb10 and Δb14 are less than 0.1 units.

Not any “not allowed” multipole appears because the four-fold symmetry is always respected

b6Holes diameter of 110mm

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

0 2000 4000 6000 8000 10000 12000 14000 16000

I (A)

b6

(un

it)

4 hole 45º, centered

4 holes 0º, centered


Iron yoke: choice of the hole diameter and position

From the integration point of view the best solution would be 4 holes of 110mm diameter located at the mid-plane

From the magnetic point of view: the case of the 4 holes of 110mm diameter seems to be acceptable because the reduction of the transfer function is lower than what we have for the MQXA (5.2%) and the Δb6 is a bit lower than the other cases.we expect to be able to improve the field quality by modifying the cross section (see following slides) or directly in the iron


MQXC cross sections and iron yoke

Due to the presence of the holes and due to the slight changes in the cross-section designs (due to the multipoles optimization) the short sample parameters have to be re-computed

The presence of 110mm holes at the mid-plane only reduces the short sample gradient by 0.2-0.5%

Transfer function of the 4 MQXC cross-sections

The reduction of the transfer function of the 4

MQXC cross- sections is in between what we

have for the MQXA and MQXB

TF

94

95

96

97

98

99

100

101

0 0.2 0.4 0.6 0.8 1 1.2

I/In

(B2

/I)/(

B2

0/I0

) (%

)

MQXC (110mm) V13

MQXC (120mm) V8

MQXC (130mm) V2

MQXA

MQXB

Full iron110 mm hole at the mid-

plane ΔGss ΔIss

magnet ap

(mm) Gss (T/m) Iss (A) Gc (T/m) Iss (A) (%) (%)

MQXC V13 110 158.4 15213 158.0 15375 -0.2 1.1

MQXC V8 120 148.6 15900 147.9 16113 -0.5 1.3

MQXC V2 130 138.7 14805 138.0 15088 -0.5 1.9


MQXC cross sections and iron yoke

Multipoles after optimizing the coil blocks positionMultipoles (MQXC V13) 110mm

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 2000 4000 6000 8000 10000 12000 14000current (A)

mu

ltip

ole

s (u

nit

s)

b6

b10

b14

Multipoles (MQXC V8) 120mm

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 2000 4000 6000 8000 10000 12000 14000

current (A)

mu

ltip

ole

s (u

nit

s)

b6

b10

b14


-1.0

-0.5

0.0

0.5

1.0

1.5

0 2000 4000 6000 8000 10000 12000 14000

current (A)

mu

ltip

ole

s (u

nit

s)

b6

b10

b14

We tried to optimize the cross-sections to cancel the multipoles b6, b10 and b14: We didn’t manage to further reduce b10 and b14

Multipoles b10 and b14 are almost insensitive to the iron saturation.We have to try to reduce the multipoles by playing with the iron yoke


Conclusion I

We studied a first set of three designs of 110, 120 and 130mm apertures which almost reach the maximal short sample gradient expectedWe first set the field quality constrain to 1 unit, expecting to further reduce the multipoles after yoking (by re-optimizing the cross-section)Yoking: we studied the effect of the holes in the iron needed for the He flow. It seems that the best option from the integration point of view (four 110mm holes at the mid-planes) is acceptable from the magnetic point of viewWe found that the short sample gradient is only reduce by ~0.5% when four 110mm holes are inserted at the mid-planes. We tried to re-optimized the cross-sections to cancel the multipoles b6, b10 and b14 but we didn’t manage to reduce b14 below 0.7 units and b10 below 0.3 units. However we have not tried to play on the iron shape yet…remains to be done


Preliminarily designs for a possible second cables distribution


MQXC: NEW cross-sections

We are looking for some other designs in order to improve the field qualityBelow is a possible second set of MQXC quads. It is just some preliminarily results, lot of work remains to be done.

110mm (MQXC V16) 120mm (MQXC V15) 130mm

Under study!…

TF

94

95

96

97

98

99

100

101

0.0 0.2 0.4 0.6 0.8 1.0 1.2

I/In

(B2

/I)/(

B2

0/I0

) (%

)

MQXC (110mm) V16

MQXC (120mm) V15

MQXA

MQXB

We still consider an iron yoke with 110mm hole located at the mid-plane

The reduction of the transfer function is still smaller than for the MQXA (5.2%). For the 110mm design (MQXC V16) it is even smaller than the MQXB


MQXC: NEW cross-sections

All the multipoles are very closed to zero (at least below 0.1 unit) at nominal current (80% of the short sample), but the short sample gradient is 2-3% smaller than the previous MQXC design


-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 2000 4000 6000 8000 10000 12000 14000

b6

b10

b14


-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 2000 4000 6000 8000 10000 12000 14000 16000

b6

b10

b14

nb turn previous desings

magnet ap (mm) Gss (T/m) Iss (A) cable 01 cable 02 Gss (T/m) ΔGss (%)

MQXC V16 110 153.9 17725 16 12 158.0 2.8

MQXC V15 120 145.8 16600 18 15 147.9 1.9

MQXC V17 130 ? ? ? ? 138.0 ?


CONCLUSION iI

We studied a new set of possible MQXC cross-sections: 110, 120 mmWe managed to get a good field quality (all multipoles below 0.1 unit) at nominal currentThe short sample gradients are 2 to 3% smaller than the first set of designs

FUTURE WORKTrying to reduce the multipoles in the first set of MQXC designs by playing with the yokeDesigning other cross-sections with new cables distributions

Quadrupole design study for the lhc phase I upgrade (3 rd iteration)

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