11 T Dipole for DS

11 T Dipole for DSM. Karppinen TE-MSC-ML

On behalf of CERN-FNAL collaboration

B. Auchmann, L. Bottura , B. Holzer, L. Oberli, L. Rossi, D. Smekens (CERN)

N, Andreev, G. Apollinari, E. Bartzi, R. Bossert, F. Nobrega, I. Novitski, A. Zlobin (FNAL)

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Collimation Phase II Upgrade in DS

• 2013: IR3 (Decision in June)• 2017: IR7 & IR2 (IR3?)• 2020: IR1,5 as part of HL-LHC• Base-line is re-location of magnets to create

space for 4.5 m long warm collimator• Cryo-collimator is an R&D project

May 2, 2011

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DS Upgrade Scenarios

-4.5 m shifted in s

halo

+4.5 m shifted in s

transversely shifted by 4.5 cm

halo

Shift 12 Cryo-magnets, DFB, and connection cryostat in each DS

New ~3..3.5 m shorter Nb3Sn Dipoles (2 per DS)

May 2, 2011

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Cryo-collimator

1541

3061

Courtesy of D. RamosMay 2, 2011

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Strong DS-Dipole• Plan A (Cryo-collimator, L ≈ 3 m):

– 1 x (11.2 T x 10.6 m) magnet, Lcoldmass ≈ 11 m, (MB -4.2 m) => 8 coldmass + 2 spares = 10 CM by 2017– 2 x (11.2 T x 5.3 m) magnets, Lcoldmass ≈ 11.5 m, (MB -3.7 m) => 16 coldmass + 4 spares = 20 CM by 2017

• Plan B (Warm collimator, L = 4.5 m):– 4 x (11 T x 5.3 m) dipoles, Lcoldmass ≈ 23.0 m – Approx. 7.3 m for collimator and local orbit / higher order

correctors (and ICs, bus-bar lyras etc..) => 32 coldmass + 8 spares = 40 CM by 20??

May 2, 2011

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Magnet Design Constraints• ∫BdL = 119.2 Tm @ Inom = 11.85 kA• 2-in-1 design, intra-beam distance 194 m• Aperture: Sagitta: 11 m – 5.0 mm, 5.5 m – 1.3 mm

=> Ø60 mm aperture and straight cold mass • Cold mass outer contour from MB• Heat exchanger location as in MB• 20 % operation margin on the load-line• Field harmonics at 10-4 level (TBC by AP)• Maximum use of existing tooling and infrastructure in both

labs

May 2, 2011

Nb3Sn Superconductor

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• Nb3Sn critical parameters (Jc, Bc2 and Tc) very attractive for accelerator magnets

• Requires (long) heat treatment @ 680 °C=> Only inorganic insulation materials

• Brittle, strain sensitive after reaction• Requires vacuum impregnation with resin

=> less efficient heat extraction by He

• Magneto-thermal instabilities => small filaments, small strands, high RRR

• Filaments ~50 µm (NbTi 6 µm) Persistent current effects

• Cost ~5 x NbTi• Limited supply and only few suppliers

(compared to NbTi)

Nb3Sn Accelerator Magnet R&D Progress

May 2, 2011 9M. Karppinen TE-MSC-ML

Both the performance and the technological aspects of the Nb3Sn strands and accelerator magnets have significantly advanced.

Year Laboratory Magnet type (name) Results1967 BNL quadrupole 85 T/m (3 T)1979 BNL dipole 4.8 T1982 CERN quadrupole 71 T/m1983 CEN/Saclay dipole 5.3 T1985 LBNL dipole (D10) 8 T1986 KEK dipole 4.5 T1988 BNL dipole 7.6 T1991 CERN/ELIN dipole 9.5 T1995 LBNL dipole (hybrid D19H) 8.5 T1995 UT dipole (MSUT) 11.2 T1996 LBNL dipole (D20) 13.3 T2003 LBNL dipole (RD3c) 10 T

2004-6 Fermilab dipole (HFDA05-07) 10 T2008 LBNL dipole (HD2) 13.4 T

A. Zlob

in, PA

C-201

1

• Nb3Sn accelerator magnet R&D at Fermilab since 1999 focusing first on small aperture 10 T dipoles for VLHC

• Since 2005 focus on large aperture 200 T/m quads for the LHC upgrade.

Nb3Sn Magnet R&D at Fermilab

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A. Zlobin, PAC-2011

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11 T Model Program

May 2, 2011

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Mid-20132-in-1 #2

CERN Coils

End-20111-in-1 Demo

End-20135.5 m Model

End-20122-in-1 #1

FNAL Coils

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Production Phase 2014-17• Coil production (CERN & FNAL)• Collaring (CERN & FNAL)• Cold mass assembly (CERN)• Cryostat integration (CERN)• Testing (CERN)• Installation in the tunnel• Material cost for 20 off 5.5 m CM ~25 MCHF

3..4 years

May 2, 2011

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Cable & Insulation

May 2, 2011

250 m Nb3Sn cable produced Jc measurements underway

First CERN cabling run expected Beg-May

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Measured Jc (rectangular cable)

May 2, 2011

Courtesy of E. Barzi, FNAL

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Working point & EM ForcesMeasured JcOST 108/127Ø0.70 mm10% degr.

80.4%

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Coil Ends & Practice Coil

17May 2, 2011

Yoke cut-back determined such that the Bp is in the straight section

First practice coil wound with SLS end spacers

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2-in-1 & 1-in-1 Models

May 2, 2011B0(11.85 kA) = 11.21 T

18B0(11.85 kA) = 10.86 T

• The 25-mm thick slightly elliptical stainless steel collar.

• The vertically split iron yoke clamped with Al clamps.

• The 12-mm stainless steel skin. • Two 50-mm thick end plates.• The coil pre-stress at room temperature

is 100 MPa to keep coil under compression up to 12 T.

• The mechanical structure is optimized to maintain the coil stress below 160 MPa - safe level for brittle Nb3Sn coils.

1-in-1 Demonstrator Mechanical Structure

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The structure and assembly tooling design is in progress.A. Zlobin, PAC-2011

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Design Parameters

May 2, 2011

Note: Cryostat, beam-screen, beam-pipe, (slight) permeability of collars not included

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AP: Effects to be expected

• magnets are shorter than MB Standards change of geometry

distortion of design orbit by ~7 mm

• non-linear transfer function (3.5 TeV) distortion of closed orbit

~15..20 mm

• R-Bends S-Bends edge focusing

• feed down effects from sagitta ?

• multipole effect on dynamic aperture ?

Analytical approach / Mad-X / Sixtrack Simulations

beta beat: tune shift:

Courtesy of B. Holzer

May 2, 2011

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difference in radial coordinatestandard LHC – Nb3Sn LHClocal result

Δx ≈7 mm

Courtesy of B. Holzer

May 2, 2011

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MCBM 1.9 Tm @55 AMCBCM 2.8 Tm @100 AMCBYM 2.6 Tm @ 88 A

Transfer Function Correction

May 2, 2011

Below Inom 11 T Dipole is stronger than MB

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The Story of the Transfer Function ... a closed orbit problem effect of nb3sn field error (1.5 Tm)

two dipolesdistorted orbit,but partially compensated in a closed 180 degree bumpΔΦ = 4.545 ≈ modulo180 degree

Δx ≈ ± 15 mm

one Nb3Sn magnet

Courtesy of B. Holzer

May 2, 2011

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The Story of the Transfer Function ... a closed orbit problem

effect of nb3sn field error (1.5 Tm) two dipolesdistorted orbit,and corrected by the “usual methods”

corrected by 20 orbcor dipoles

x(m) x(m)

Δx ≈ -0.5 ... + 1.5 mm ≈ 5 σ at 3.5 TeV

Courtesy of B. Holzer

May 2, 2011

two Nb3Sn magnets

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The Story of the Transfer Function ... a closed orbit problem

field error corrected by 3 (20) most eff. correctorszooming the orbit distortion

... local distortion due to Δϕ ≈ 4.545 phase relation, closed by MCBH correctors

MCBH corrector strength:

available: 1.900 Tm needed: 0.805 Tm= 42 %

!

Courtesy of B. Holzer

May 2, 2011

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C8 C9 C10 C11 C8

RB.A23

Total inductance:15.5 H (152x0.1H + 2x0.15H)Total resistance: 1mWOutput current: 13 kAOutput voltage: 190 V

Trim1

Trim2

Main Power Converter

0.1H

0.15H

Total inductance: 0.15 HTotal resistance: 1mWRB output current: ±0.6 kARB output voltage: ±10 V

TRIM Power Converters

(+)• Low current CL for the trim circuits• Size of Trim power converters

(-)• Protection of the magnets• Floating Trim PCs (>2 kV)• coupled circuits

New RB Circuit (Type 1)

Courtesy of H. ThiessenMay 2, 2011

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Nested Trim Circuit

May 2, 2011

11 T Dipole current needs to be reduced

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Coil MagnetizationMB (NbTi) 11 T Dipole Nb3Sn

May 2, 2011

Mid-Plane Inner LayerMid-plane Outer layerInner Layer PoleOuter Layer Pole

>10 X

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Persistent Current Effects

May 2, 2011

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Persistent Current Effects

May 2, 2011

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Additional Correctors?

May 2, 2011

MCS B3 = 0.0518 TmMCD B5 = 0.000266 Tm

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Higher Multipoles

May 2, 2011

11 T Dipole Main Dipole

b9

b9

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Sagitta: Δr = s

l

ρ

φ aperture feed down effects

Feed Down Effects:

Bdl I b3(syst) b3(pc) Σb3 Bρ

450 GeV 7.7 Tm 758 A 13.96 +95.8 109.8 1.5*103 Tm3.5 TeV 59.6 Tm 5639 A 13.99 -4.72 9.27 1.2*104

Tm7 TeV 119.1 Tm 11517 A 13.37 +0.44 13.81 2.3*104 Tm

Courtesy of B. Holzer

May 2, 2011

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Feed Down Effects:

Quadrupole Error:

k1l ΔQ Δβ/β

450 GeV 2.79*10-3 0.031 20%

3.5 TeV 2.35*10-4 0.00262 1.76%

7 TeV 2.41*10-4 0.00268 1.80%

Phase 1 D1 b3=3*10-4 0.0059 3.9%

Tuneshift: Beta Beat

per Magnet considered as tolerance limit (DA)

Courtesy of B. Holzer

May 2, 2011

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dynamic aperture for ... ideal Nb3Sn dipoles (red) full error table (green)

and for completeness: limits in DA for the phase 1 upgrade study (blue)

for the experts: the plot shows the minimum DA for the 60 error distribution seeds used in the tracking calculations.

Field Quality: Dynamic Aperture Studiescollision optics, 7 TeV

dyn aperture luminosity optics, 7 TeV, minimum of 60 seeds

Courtesy of B. Holzer

May 2, 2011

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dynamic aperture for Nb3Sn case: full error table (red) b3 reduced to 50% (green)b3 reduced to 25% (violett)b3 = 0 and to compare with: present LHC injection

for the experts: unlike to the collision case: at injection the b3 of the Nb3Sn dipoles is the driving force to the limit in dynamic aperture.A scan in b3 values has been performed and shows that values up to b3 ≈ 20 units are ok. Alternative solution: strong local spool piece corrector ... which is being studied at the very moment.

Field Quality: Dynamic Aperture Studiesinjection optics, 450 GeV, no spool piece correctors

dyn aperture injection optics, minimum of 60 seeds

Courtesy of B. Holzer

May 2, 2011

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Summary (1/2)• The magnet technology exists and can meet the

requirements. Base-line is 5.5 m long CM.• Magnet design is based on engineering choices proven by

the HFM programs and LHC magnet production. • The 2 m 1-in-1 demonstrator magnet is well underway

and the engineering design of the 2-in-1 demonstrator is in progress.

• First optics studies: – Orbit can be corrected by using a significant factor of corrector

strength outside of DS. Trim PC would solve the problem.– b3 @450 GeV can be tolerated up to ˜20 units, which seems

achievable (passive shimming, B3 corrector..).

May 2, 2011

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Summary (2/2)• The integration into the LHC is common effort

with with the (cryo-) collimator R&D.• The time scale of the planned upgrade is

challenging and requires close collaboration and parallel production lines at CERN and at FNAL.

May 2, 2011

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Refs[1] A.V. Zlobin, G. Apollinari, N. Andreev, E. Barzi, V.V. Kashikhin, F. Nobrega, I. Novitski , B.

Auchmann, M. Karppinen, L. Rossi “Development Of Nb3sn 11 T Single Aperture Demonstrator Dipole For Lhc Upgrades”, presented at PAC-2011, New York, March 2011.

[2] G. de Rijk, A. Milanese, E. Todesco, “11 Tesla Nb3Sn dipoles for phase II collimation in the Large Hadron Collider”, sLHC Project Note 0019, 2010.[2] A.V. Zlobin et al., “Development of Nb3Sn accelerator magnet technology at Fermilab”, Proc. of PAC2007, Albuquerque, NM, June 2007.[3] J. Ahlbäck et al., “Electromagnetic and Mechanical Design of a 56 mm Aperture Model Dipole for the LHC“, IEEE Trans. on Magnetics, July 1994, vol 30, No. IV, pp. 1746-1749[4] G. Ambrosio et al., “Magnetic Design of the Fermilab 11 T Nb3Sn Short Dipole Model”, IEEE Trans. on Applied Supercond., v. 10, No. 1, March 2000, p.322.[5] M.B. Field et al., “Internal tin Nb3Sn conductors for particle accelerator and fusion applications,” Adv. Cryo. Engr., vol. 54, pp. 237–243, 2008.[6] G. Chlachidze et al., “The study of single Nb3Sn quadrupole coils using a magnetic mirror structure,” presented at ASC’2010, Washington, DC, 2010. [7] V.V. Kashikhin and A.V. Zlobin, “Correction of the Persistent Current Effect in Nb3Sn Dipole Magnets”, IEEE Trans. on Applied Supercond., v. 11, No. 1, March 2001, p. 2058.

May 2, 2011

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Acknowledgements

R. Assmann, R. Denz, G. De Rijk, P. Fessia, A. Milanese, R. Ostojic, D.Ramos, H. Thiessen,

E. Todesco

May 2, 2011