conceptual design of the new d1 magnet for hl-lhc upgrade - present status -

1

Conceptual Design of the new D1 Magnet for HL-LHC upgrade

- Present Status -

T. Nakamoto (KEK), Q. Xu (KEK/CERN)M. Iio (KEK), E. Todesco (CERN)

8 May 2012, LARP CM18/HiLumi LHC Meeting

2

Objective

Schematic layout of the LHC

Current D1 (MBXW) at IR1 & IR5

• For HL-LHC upgrade, needs for new Inner Triplet system at IR1 & IR5.– Large aperture HF Quadrupoles (120 or 140 mm),

corrector package.• New beam separation dipole (D1) should be

accommodated with large aperture IT Quads. • Replacement of current conventional magnets (nominal

field 1.28T) by large aperture superconducting dipole magnets.

• Conceptual design study is underway at KEK and CERN.

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Design Guideline for the new D1• Coil ID: 150 mm for the 140 mm triplet

130 mm for the 120 mm triplet• Integrated field: 40 Tm, 50% larger than today (given by R. De Maria) • Operational margin: 70 % of the loadline (lot of radiation, margin needed)• Top: 1.9 K • Coil lay out: Two layers of 15 mm cable (thick coil to have larger

field, lower stress, lower current density)• Conductor: Nb-Ti is baseline. (Leftover of LHC MB cables.)• Support structure: Collaring yoke structure (RHIC main dipole, MQXA, J-PARC

SCFM)

• Field homogeneity: ~ 10-4 at 2/3 bore radius • Cold mass OD: 570 mm (same as MB)

>> Fringe fields will be an issue.• Radiation, energy deposition "order of 10 MGy, 1021 /m2, 10 W/m" ??

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Design Parameters w/ NbTi LHC MB inner cableItem Value Ratio

Bore diameter 150 mm (MBXE) 130 mm (MBXD) 1.15

Nominal field (dipole) 6.35 T 6.48 T 0.98

Operating current 9.3 kA 9.2 kA 1.01

Field homogeneity <0.01% (Rref=50/43 mm) /

Peak field in the coil 7.06 T 7.08 T 0.997

Load line ratio(Inner / Outer layer)

70% / 63.7% @1.9 K 90% / 81.8% @4.2K

70% / 64.8% @1.9 K 90% / 83.3% @4.2K

1

Inductance (low field / nominal field )

16.1 / 13.6 mH/m

12.8 / 10.6 mH/m

1.28

Stored energy 588.1 kJ/m 448.6 kJ/m 1.31

Peak field/central field 1.11 1.09 1.02

Lorenz force X/Y 2.1/0.97 MN/m 1.96/0.86 MN/m /

Estimated coil stress 71 MPa 57 MPa 1.25

Outer dia. of iron yoke 550 mm /

Inner dia. of iron yoke 254 mm 234 mm 1.09

Strand diameter 1.065 /

Cu/Non-Cu ratio 1.65 /

Cable dimension / insulation 15.1* 1.9mm2 / 0.16 mm (radial) 0.135 (azimuthal)

/

No. of strands 28 /

Keystone angle 1.24 ° /

Supercon. current density 1000 A/mm2 989 A/mm2 1.01

Bore diameter 130 mm

Bore diameter 150 mm

0 1 2 3 4 5 6 7 8 9 10-20

-15

-10

-5

0

5

10

15

20

25

30

35

40130 mm aperture - b3150 mm aperture - b3

Current (kA)

Nor

mai

l and

skew

mul

tiple

s (1e

-4)

MF Design with NbTi LHC dipole inner cable

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Transfer function of the 2 cases with the collar width of 20 mm.

The dependence of b3 on the operating current caused by iron saturation and filament magnetization.

0 1 2 3 4 5 6 7 8 9 100.640000000000004

0.660000000000004

0.680000000000004

0.700000000000004

0.720000000000004

0.740000000000004

0.760000000000004

0.780000000000004

Operating current (kA)

Tran

sfer

func

tion

(T/k

A)

Bore diameter: 150 mm


Collar thickness 20 mm

b3 variation due to iron saturation & fringe field

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Fringe Field of the New D1 Magnet

Stray field at the outer surface of the iron cryostat (ROXIE simulation results): 0.14 T at max.

Magnetic field in the iron yoke and iron cryostat for 150 mm aperture and at nominal current(ROXIE simulation results)

90 o

270 o

0 o180 o

Field Distortion Coupled w/ Stray Field

• Stray field will be issues of environment.• Magnetic force between the cold mass and the iron cryostat must be considered.• Off-centered cold mass position in the current MB cryostat affects the field quality.

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(A) Optimized without iron cryostat

(B) With an centered iron cryostat.

(C) With an off-centered iron cryostat.

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00.020.040.060.08

0.10.120.140.160.18

Yoke outer diameter (m)

Frin

ge fi

eld

outs

ide

of th

e cr

yost

at(T

)

Measures for Stray Field: Increase of iron thickness

Maximum fringe field at the outer surface of the cryostat with different sizes of iron yoke for 150 mm aperture (with 12 mm thick vacuum chamber and 20 mm thick collar)

Maximum fringe field at the outer surface of the cryostat with different thickness of vacuum chamber for 150 mm aperture (with 550 mm iron yoke)

Weight: 1.5 ton/m

Weight: 4 ton/m12 24 36 48 60 720

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

Thickness of the vacuum vessel (mm)

Frin

ge fi

eld

outs

ide

of th

e cr

yost

at (T

)

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Measures for Stray Field: Shield coil method By using 6 turns of busbar (with the position angle of 22 degrees ) as the shield coil:the fringe field at the outer surface of the cryostat can be reduced from 0.14 T to ~ 0.04 T; The operating current is increased from 9.3 kA to 9.5 kA to keep the 70% load line ratio; the main field in the aperture is reduced from 6.35 T to 6.28 T.

90 o

270 o

0 o180 o

shield coil

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Magnetic Field & Force on the Shield CoilMagnetic field

Lorentz force

Peak field of the shield coil: 2.1 T

Peak field of the main coil: 7.0 T

Main coilFx: 2.0 MN/mFy: -1.0 MN/m

Shield coilFx: 0.02 MN/mFy: 0.02 MN/m

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Position Dependence of the Shield Coil on b3With optimized coil layouts for different position angles of the shield coil

0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5 9.5-25

-15

-5

5

15

25

35

45

6-turn with 22 degree




Mul

tipol

e co

effici

ents

b3

InjectionOperating current

Target: Stray Field below 50 mT

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Field Quality for Each CaseWith optimized coil layout for each case to reduce multiples (b3 ~ b13) less than 1 unit

0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5 9.5-20

-10

0

10

20

30

40150 mm aperture magnet

magnet with cryostat

magnet with cryostat and shield coil (33 degree)


Mul

tipol

e co

effici

ents

b3

InjectionOperating current

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Variation of Multipole CoefficientsAll available normal and skew multiples

0 1 2 3 4 5 6 7 8 9 10-20

-10

0

10

20

30

40b3 b5 b7b9 b11 b13a2 a4 a6

Current (kA)

Nor

mai

l and

skew

mul

tiple

s (1e

-4) 150 mm aperture magnet with

cryostat and shield coil (8 turns at 33°)

0 1 2 3 4 5 6 7 8 9 10-1.0

0.0

1.0

2.0

3.0

4.0

5.0b5 b7 b9 b11b13 a2 a4 a6

Current (kA)

Nor

mai

l and

skew

mul

tiple

s (1e

-4)

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Mechanical simulation model in ANSYS

Spacer

Simulation steps• Collaring < 10 MPa pre-stress generated in coil

by using a 0.1mm “virtual” gap between coil and mid-plane insulation;

• Yoking (2 steps) 1. load applied on the yoke shoulder

to close the ~1mm gap between the top yoke (and spacer) and mid-plane;

2. remove load, insert the lock-key.• Shell welding Including stress from shell;• Cool-down to 2K• ExcitationBoundary conditions• Symmetry condition in X/Y direction:

UX = 0 in line X = 0; UY = 0 in line Y = 0;

• Friction coefficient of 0.2 for all internal interfaces;

Iron yoke

Stainless steel Shell

Key

Coil

Gap thickness between top yoke and mid-plane: 0.95 mm (inner) / 1.23 mm (outer);

UX = 0

UY = 0

•Collaring yoke structure (like RHIC main dipole, MQXA, J-PARC SCFM…)•2D global model w/ tapered MP.

- The model w/ detailed key slot feature will be made later.

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Yoking: load on the yoke shoulder

2.8 MN/m load applied on the shoulder of the iron yoke;The gap between top and bottom yokes closed at the inner end. The outer end is still opening.

UX = 0

UY = 0

Spacer

Coil

Stress intensity

Displacement in Y direction

Boundary conditions

Yoke

Load: 2.8 MN/m

Gap UY: 1 mm UY: 1.07 mm

Excitation

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Including the Lorentz force transferred from the magnetic simulation results; The gap between top and bottom yokes closed at both ends.

UY: 0.95 mm UY: 1.16 mm

Stress distribution

Displacement in Y directionUX = 0

Spacer

Coil

YokeFix the midline of the lock-key

~1.15 mm displacement in x direction

UY = 0

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Coil Stress at Each Step

Yoking with key

Excitation at cold

Unit: Pa

Average coil stress in mid-plane

Average coil stress in pole region

•Coil pre-stress at assembly: < 100 MPa•Compressive stress remains after cool-down and 110 % excitation.•Creep effect is not taken into account.

Radiation Resistant Materials• Development of insulation coating

technologies on metal parts (i.e. end spacers, wedges)– Ceramic spray– Polyimide coating by Vapor

Deposition Polymerization technology.

• Materials development using BT (Bismaleimide Triazine) resin and Cyanate Ester/Epoxy resin.– Epoxy: NG!!– Necessary for the new D1!!– Prepreg tape (curing at 150 °C)– GFRP

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(T. Sasuga, Polymer Vol. 27, 1986, 681)

BT resin: e irradiation

Materials have been developed.Irradiation tests up to 100 MGy are planned at JAEA Takasaki, KURI

Polyimide coating

Alumina plasma spray

After 1.9K(SUS plates)

To be addressed• Constraint of a unit cable length (leftover for MB)

– 460m for inner cable, 780m for outer one.>> Start to design with the outer cable.

• Structure with cooling capability to be implemented.– holes for internal HeII-HX (f80-100mm) – insulation for cables, collars.

• Quench protection studies.• Coil end design: field optimization, stress.• Mechanical FEM analysis w/ detailed key slot feature.• Field quality adjustment: holes, collar.• Measure for stray field

– Feasibility study of shield coil (ends, support structure)– Option of centered magnet wrt cryostat– Magnetic force affected by environments: cryostat, test-stand.

• "Is field quality acceptable for the accelerator operation??"19

NbTi MQXC at CERN will be a good reference.

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Backup

Higher Harmonics (other than b3)

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0 1 2 3 4 5 6 7 8 9 10-2.0

-1.0

0.0

1.0

2.0

b5 b7 b9 b11 b13

Current (kA)

Nor

mai

l and

skew

mul

tiple

s (1e

-4)

150 mm aperture

0 1 2 3 4 5 6 7 8 9 10-2

-1

0

1

2

b5 b7 b9 b11 b13

Current (kA)

Nor

mai

l and

skew

mul

tiple

s (1e

-4)

130 mm aperture

22

Fringe field vs. turn no. of the shield coil

0 1 2 3 4 5 6 7 8 9 10

-0.02

1.04083408558608E-17

0.02

0.04

0.06

0.08

0.1

0.12

0.14

Position angle - 22 degree



Turn no. of the shield coil (busbar)

Frin

ge fi

eld

at th

e ou

ter s

urfa

ce o

f the

cryo

stat

(T)

MF Design with NbTi LHC dipole inner cable

23

Transfer function of the 2 cases with the collar width of 20 mm.

The dependence of b3 on the operating current caused by iron saturation and filament magnetization.

0 1 2 3 4 5 6 7 8 9 100.640000000000004

0.660000000000004

0.680000000000004

0.700000000000004

0.720000000000004

0.740000000000004

0.760000000000004

0.780000000000004


Tran

sfer

func

tion

(T/k

A)



0 1 2 3 4 5 6 7 8 9 10-5

0

5

10

15

20

25


Mul

tipol

e co

effici

ents

b3

Bore diameter 150 mmCollar thickness 20 mm

Bore diameter 130 mm Collar thickness 25 mm

Bore diameter 130 mm Collar thickness 20 mm

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Yoking – Key insertion

Remove load from yoke shoulder and applied the same load on the lock-key;The gap between top and bottom yokes closed at both ends.

UX = 0

UY = 0

Spacer

Coil

Stress intensity


Boundary conditions

Yoke

Load: 2.8 MN/m

UY: 1 mm UY: 1.35 mm

25

Shell welding

Including the shell stress by inserting a virtual gap between yoke and shell;The gap between top and bottom yokes closed at both ends.

UX = 0

UY = 0

Spacer

Coil

Stress intensity


Boundary conditions

Yoke

Load: 2.8 MN/m


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Cool-down to 2K

The gap between top and bottom yokes closed at both ends.

UX = 0

UY = 0

Spacer

Coil

Stress intensity


Boundary conditions

Yoke

Load: 2.8 MN/m


Resource and Constraint• NbTi SC cable for MQXC (leftover of the LHC main dipole cable with new insulation

system enhancing cooling capability) is the baseline.• Reuse of tooling, jigs, and facilities of the J-PARC SC Combined Function Magnets.• Yoke OD of 550 mm, same as the LHC main dipole. Yoke inner shape could be

modified.• Press jig for collaring-yoke (3.6 m long) can be used as is.

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conceptual design of the new d1 magnet for hl-lhc upgrade - present status -

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