Next European Dipole (NED) Status Report

Arnaud DevredCEA/DSM/DAPNIA/SACM &

CERN/AT/MASon behalf of the NED Collaboration

HHH General MeetingCERN

11 November 2004

NED Phase I

• The Phase I of NED is articulated around four Work Packages

and a Working Group

1 Management & Communication (M&C),

2 Thermal Studies and Quench Protection (TSQP),

3 Conductor Development (CD),

4 Insulation Development and Implementation (IDI),

5 Magnet Design and Optimization (MDO) Working

Group.

TSQP Work Package

• The TSQ Work Package includes two main Tasks

– development and operation of a test facility to

measure heat transfer to helium through conductor

insulation

(CEA and WUT; Task Leader: B. Baudouy, CEA),

– quench protection computation

(INFN-Mi; Task Leader: G. Volpini).

Heat-Transfer Measurement Task (1/2)

• CEA has designed a new

pressurized, He-II, double-

bath cryostat.

• The cryostat is being

manufactured under WUT

supervision and is scheduled

for delivery to Saclay in the

first quarter of 2005.Radiation shields

Vacuum container

Heat exchanger piping

Heat exchanger

Expansion valve

Pumping

He IIp

He IIs

LHeGHe

Insert

Cryogenic vessel

He I

Experimental volume

Schematic of double-bath cryostat for heat-transfer measurements(courtesy F. Michel, B. Baudouy and B. Hervieu, CEA)

Heat-Transfer Measurement Task (2/2)

• Measurements will be performed for various insulation

systems and on two types of samples: 1-D drum samples, to

study basic phenomenon and stack samples representative of

actual magnet coils. 11 mm 1.47 mmCuNi strand wiresthermometerStycastelectrical insulation tapes

Stack Sample(courtesy N. Kimura,

KEK)

Drum Sample(courtesy B. Baudouy,

CEA)

Magnet Cooling

• In complement to the heat-transfer measurement Task

– D. Richter (CERN) will analyze available LHC magnet

test data at high ramp rate to determine how well these

measurements on actual magnets correlate with the

Saclay measurements for a similar insulation system,

– R. van Weelderen (CERN) has undertaken a review of

magnet cooling modes to estimate, on the cryogenics

system point of view, the limitations on power extraction

and provide guidance on how to improve cooling of

magnet coils.

Quench Protection Task (1/2)

• INFN-Mi has completed a survey of thermal properties and

has studied how the error bars on the data may influence the

results.

0.E+00

1.E+16

2.E+16

3.E+16

4.E+16

5.E+16

6.E+16

7.E+16

0 100 200 300

Temperature (K)

U (A^2 s m^-4)

Comparison of MIITs computations for impregnated NED cables relying on different data sources(courtesy M. Sorbi, INFN-Mi)

Quench Protection Task (2/2)

• INFN-Mi is now undertaking systematic quench protection

studies, starting from the 88-mm-aperture, cos, layer design

chosen as reference for NED.

0

50

100

150

200

250

300

0 10 20 30 40

Rd (ohm x 1E-3)

Hot spot Temp. (K)

Layer1

Layer2

Layer 1 unif.

Layer2 unif.

0

100

200

300

400

500

600

0 10 20 30 40

Rd (ohm x 1E-3)

Max voltage (V)

Layer1

Layer2

Hot-spot temperature computations using the QLASA code for the NED, 88-mm-aperture, cos, layer baseline design(courtesy M. Sorbi, INFN-Mi)

TSQP Planning

• Collaboration

between CEA and WUT

is off to a good start –

enthusiasm of team

compensates lack of

human resources.

• All tasks are on

time!

WBS#

TitleOriginal

begin date(Annex 1)

Originalend date

(Annex 1)

EstimatedStatus

Revisedend date

2.1TSQP WPCoordination

2.2Heat TransferMeasurements

2.2.1 Specifications1 January2004

31 March2004

Completed8 June2004

2.2.2Cryostat design andmanufacturing

1 April2004

31 Dec.2004

Ongoing On time

2.2.3Heat exchangermanufacturing

1 April2004

31 Dec.2004

Ongoing On time

2.2.4Facility integrationand commissioning

1 January2005

31 March2005

Not started -

2.2.5Measurements anddata analysis

1 April2005

31 Dec.2006

Not started -

2.3Quench protectioncomputation

1 April2004

30 June2005

Ongoing On time

CD Work Package

• The CD Work Package includes four main Tasks

– preliminary magnet design aimed at deriving

meaningful conductor specifications (CERN; Task

Leader: D. Leroy),

– wire and cable development through two industrial

sub-contracts, investigating two different manufacturing

processes: Enhanced Internal Tin and Powder in Tube,

(under CERN supervision; Task Leader: D. Leroy),

– wire and cable characterization

(CEA, INFN-Ge, INFN-Mi, and TEU; Task Leader: A. den

Ouden, TEU),

– mechanical FE analysis of cabling effects

(INFN-Ge; Task Leader: S. Farinon).

Preliminary Design Task (1/3)

• To derive meaningful conductor specifications, CERN has

investigated two types of cos dipole magnet designs: a layer-

type and a slot-type.

• The investigation was carried out for three apertures: 88 mm,

130 mm and 160 mm and aimed at a 13-to-15-T bore field.

1.599814 MN/m1.759376 MN/m

1.366123 MN/m

1.104555 MN/m

0.522062 MN/m

1.443344 MN/m1.721069 MN/m

3.913917 MN/m2.357302 MN/m3.401580 MN/m

2.636726 MN/m

(courtesy D. Leroy and O. Vincent-Viry)

88-mm-aperture, layer type 88-mm-aperture, slot type

Preliminary Design Task (2/3)

• The preliminary design study led to the definition of strand

and cable parameters suitable to NED.

• The study shows that, at 4.2 K, the bore field stays around 14

T with a quench field of ~15 T on the conductor.

• Hence, to reach bore fields higher than 15 T the magnet

should be operated at 1.9 K.

NB: the He-II operation may also be required to improve cooling

under high beam losses.

Preliminary Design Task (3/3)

• The preliminary design study also shows that, for the two-

layer design at 14 T, the Lorentz stress accumulation in the

azimuthal direction reaches ~150 MPa for the 88 mm aperture

and is in excess of 200 MPa for the 130 and 160 mm apertures.

• A reduction in azimuthal stress accumulation can be obtained

by decreasing the overall current density in the coils while

increasing the coil thickness, which leads to a three- or four-

layer design.

• An alternative for larger apertures is to change of magnetic

configuration altogether as in the case of the slot-type design.

• To be conservative, the 88-mm-aperture, cos, layer design

has been chosen as reference design.

NED Strand Characteristics

• The main NED strand characteristics are

– diameter 1.250 mm,

– effective filament diameter < 50 m,

– Cu-to-non-Cu ratio 1.25 ± 0.10,

– filament twist pitch 30 mm,

– non-Cu JC 1500 A/mm2 at 4.2 K and 15

T,

– minimum critical current 1636 A at 12 T,

818 A at 15 T,

– N-value > 30 at 4.2 K and 15 T,

– RRR (after heat treatment)> 200.

• It is also requested that the billet weight be higher than 50

kg.

NED Cable Characteristics

• Although the final cable dimensions will only be decided later

on, the main cable parameters used in the reference, 88-mm-

aperture, cos layer design are

– width 26 mm,

– mid-thickness 2.275 mm at 50

MPa,

– keystone angle 0.22 degrees,

– number of strands 40,

– minimum critical current 58880 A at 4.2 K and 12 T,

(with field normal to broad face) 29440 A at 4.2 K and

15 T,

– RRR (after heat treatment)> 120,

– minimal cable unit length > 145 m.

• The cable critical currents assume a cabling degradation of

10%.

Conductor Development Task

• Following a market survey and a call for tender under CERN

rules, two contracts for the production of a few hundred meters

of cables have been awarded late September to

– Alstom/MSA, France (Enhanced-Internal-Tin process),

– SMI, the Netherlands (Powder-In-Tube process), with

EAS, Germany as subcontractor.

• The contracts will be monitored by CERN and extend over a

2-year period.

• Discussions are are ongoing with OAS, Finland, who may join

the program without receiving EU-funding.

Conductor Characterization Task (1/3)

• Representatives of interested parties (CEA, CERN, INFN-Ge,

INFN-Mi and TEU) have set up a Working Group on Conductor

Characterization (WGCC), Chaired by A. den Ouden, TEU.

• The WGCC is charged with the definition and development of

standardized procedures to measure the critical current,

magnetization and RRR of virgin, deformed and extracted

strands and has the responsibility for certification of the

measured data.

• Following the example of the VAMAS program, the WGCC has

initiated a cross-calibration program of critical current test

facilities, whose conclusions are due in June 2005.

Conductor Characterization Task (2/3)

• Magnetization measurements will be performed under the

supervision of INFN-Ge using a SQUID magnetometer and a

Vibrating Sample Magnetometer (VSM).

Exploratory measurements on a 5-mm-long Nb3Sn wire

sample(SQUID measurements are courtesy of C. Ferdeghini, INFM/Genova;VSM measurements are courtesy of U. Gambardella, INFN/Frascati)

• The measurements will be

performed as a function of field

to appreciate the effective

filament diameter and the

presence or not of flux jumps.

-1.5

-1

-0.5

0

0.5

1

1.5

-4 -3 -2 -1 0 1 2 3 4

4.2 K, // applied field

VSMSQUID

Magnetic Moment (emu)

B (T)

Conductor Characterization Task (3/3)

• The magnetization measurements will also be performed as

a function of temperature to study various issues, such as the

proportion of un-reacted Nb in PIT wires.

(courtesy C. Ferdeghini, INFM/Genova)

-0.0030

-0.0025

-0.0020

-0.0015

-0.0010

-0.0005

0.0000

0.0005

4 6 8 10 12 14 16 18 20

magnetic moment (emu)

T (K)

Tc Nb

3Sn=17.4 KT

c Nb

3Sn=17.4 K

Tc Nb=9.2 K

Nb3Sn shield: 0.00146 emu

total shield : 0.003 emu

Nb=65 m

(courtesy M. Greco, INFN/Genova)

Mechanical FE Analysis Task

• INFN-Ge is developing a mechanical FE model to simulate the

effects of cabling on un-reacted, Nb-Sn wires and optimize their

design.

Examples of mechanical FE model for an old “internal-tin” wire design and of Von Mises strain due to a diameter

reduction of about 40% (courtesy S. Farinon, INFN-Ge)

CD Planning

• Start date of 3.4

delayed by 3 months

due to longer contract

negotiations than

anticipated.

• End date of 3.4

delayed accordingly.

• End date of 3.5

delayed to match that

of 3.4.

• End dates of 3.6 and

3.5 not moved due to

some built-in slack in

initial program.

WBS#

TitleOriginal

begin date(Annex 1)

Originalend date

(Annex 1)

EstimatedStatus

Revised enddate

3.1 CD WP Coordination

3.2 Preliminary design1 January2004

31 Dec.2004

90%complete

On time

3.3Conductorspecifications

1 April2004

30 June2004

Completed On time

3.4 Wire development1 July2004

30 June2006

Started30September2006

3.5 Wire characterization1 July2004

30 June2006

Ongoing

3.5.1Definition ofprocedures

1 January2005

30 June2005

Ongoing On time

3.5.2Ic measurements atCEA

1 July2005

30 June2006

Started31 October2006

3.5.3Ic measurements atINFN/Mi

1 July2005

30 June2006

Started31 October2006

3.5.4Ic measurements atTEU

1 July2005

30 June2006

Started31 October2006

3.5.5Magnetizationmeasurements atINFN/Ge

1 July2005

30 June2006

Started31 October2006

3.6Cable developmentand manufacturing

1 July2005

31 Dec.2006

Not started15December2006

3.7Cablecharacterization

1 October2005

31 Dec.2006

Not started -

IDI Work Package

• The IDI Work Package includes three main Tasks

– redaction of an engineering specification and definition

of characterization tests,

(CCLRC and CEA ; Task Leader: E. Baynham),

– studies on “conventional” insulation systems relying

on ceramic or glass fiber tape and vacuum-impregnation

by epoxy resin

(CCLRC; Task Leader: E. Baynham),

– studies on “innovative” insulation systems relying on

pre-impregnated fiber tapes and eliminating the need

for a vacuum impregnation

(CEA; Task Leader: F. Rondeaux).

Insulation Specification

• A basic engineering specification for the conductor insulation

of a 15-T dipole magnet has been developed under CCLRC

supervision.

• The main parameters are

– thickness 0.2 mm per conductor face,

– dielectric strength 1 kV inter-turn in He at 300

K,

– compressive strength > 200 MPa at 300 K

and 4 K,

– short-beam shear strength > 50 MPa at 4 K,

– transverse tensile strength > 25 MPa at 4 K,

– thermal contraction 0.3-0.4% between 300 & 4

K,

– thermal conductivity > 20 mW/K at 4 K,

– thermal cycle > 10,

– running cycle > 100.

Conventional Insulation Development

• The CCLRC program on conventional insulation will address

– glass fiber sizing issues,

– radiation-hard resin alternatives, such as cyanate

esters,

– improved filler materials, such as nanoclays or

dendritic powders.

• CCLRC is also looking into fracture testing

Precrack (release film)

Crack growth from test

Example of Double Cantilever Beam(DCB) test sample(courtesy S. Canfer, CCLRC)

Innovative Insulation Development

• CEA will pursue its ongoing development on innovative

insulation

designed to enable

1) ”controlled” pre-impregnation (in particular in

terms of thickness) of glass or ceramic fiber tape,2) wrapping of un-reacted conductor

and winding of insulated conductor on small radii of curvature,

3) phase transformation of pre-impregnation during coil heat treatment so as to confer a rigid shape to the coil and eliminate the need of a subsequent vacuum impregnation of epoxy resin.

• The Task will concentrate more specifically on

– optimization of nature and weaving of the fiber tape,

– characterization and improvement of mechanical

properties after heat treatment.

IDI Planning

• Scope of 4.3.5 has

been modified to

include radiation tests

and the end date has

been moved to 30

June 2006.

• Start date of 4.4

delayed until 1

January 2005 due to

lack of human

resources at CEA

(permanent staff

contribution).

• End date of 4.4

delayed accordingly.

WBS#

TitleOriginal

begin date(Annex 1)

Originalend date

(Annex 1)

EstimatedStatus

Revised enddate

4.1 IDI WP Coordination

4.2 Specification drafting1 April2004

30 June2004

Completed 22 July 2004

4.3ConventionalInsulation

4.3.1 Literature survey1 July2004

30 Sept.2004

Completed On time

4.3.2 Tooling preparation1 October2004

30October2004

Ongoing30November2005

4.3.3 Component supply1 October2004

31 Dec.2004

Ongoing On time

4.3.4 Iterative tests1 January2005

30 Sept.2005

Not started31 Dec.2005

4.3.5 Irradiation tests1 July2005

30 June2006

Not started30 June2006

4.4 Innovative Insulation

4.4.1 Tape weaving trial1 July2004

31 Dec.2004

Not started31 Dec.2005

4.4.2 Characterization tests1 July2004

30 June2005

Not started30 June2006

MDO Working Group (1/3)

• The MDO Working Group is made up of representatives from

CCLRC, CEA, CERN and CSIC/CIEMAT

(Chairman: P. Védrine, CEA, Technical Secretary: F. Toral,

CIEMAT).

• Its main charge is to address the following questions

– How far can we push the conventional, cos, layer

design in the aperture-central-field parameter space

(especially when relying on strain-sensitive conductors)?

– What are the most efficient alternatives, in terms of

performance, manufacturability and cost?

MDO Working Group (2/3)

• The MDO WG has selected

– a number of magnetic configurations to be studied,

– ranges of design parameters,

– terms of comparison between solutions.

• Each Institute participating to the WG will completely study

one or two configurations.

• Results of the comparative study are expected by December

2005.

• Preliminary results of this study have been shared with the

Fusion community (“EFDA” Dipole).

MDO Working Group (3/3)

• Examples of alternative dipole magnet configurations to be

optimized and compared

Window-frame design proposed by CEA

(courtesy H. Felice and P. Védrine)

Motor-type design proposed by CIEMAT

(courtesy S. Sanz and F. Toral)

MDO Parameters Ranges

Peak field in conductor 15 TAperture 88-130-160 mmSuperconductor Jc 3000 A/mm2 @ 4.2K and 12 T

1500 A/mm2 @ 4.2K and 15 TCu to non-Cu ratio 1 to 2Operating margin 10 to 20 %Filling factor of cable 87 %Insulation thickness 0.2 mm per conductor faceCabling degradation 10 %X-section multipoles A few10-4 @ 2*aperture/3Overall coil length 1.3 MPeak stress 150 MPaMax coil deformation <0.05 mm (due to Lorentz

forces)Peak temperature 300 K (quench)Peak voltage to ground 1000 V (quench)Peak inter-turn voltage 100 V (quench)

MDO Terms of Comparison

1. Magnetic field:a. Central fieldb. Peak fieldc. Nominal currentd. Field qualitye. Tunabilityf. Magnetic length compared to overall lengthg. Operating margin

2. Mechanical design:a. Change of pre-stress during cooling downb. Peak stressc. Lorentz forces

3. Quench:a. Self-inductanceb. Stored magnetic energyc. Peak voltage and temperature

4. Fabrication:a. Sensit ivity to manufacturing toleranceb. Manufacturabilityc. Coil end complexityd. Minimum bending radius (parallel and perpendicular)e. Superconductor volume efficiencyf. Twin/single aperture and minimum distanceg. Costh. Number of splices

Conclusion

• All the tasks of the CARE/NED JRA have been launched and

are well under way.

• In particular, the industrial subcontracts for conductor

development have been signed at the end of September 2004,

thanks to D. Leroy diligence.

• The program is initiating the desired synergies among the

various European partners involved.

Perspectives

• There is a reasonable hope of finding the funding necessary

to carry out Phase II (model magnet manufacturing and test) at

the 2008 horizon.

• A possible scenario under consideration is a CSIC/CIEMAT-

CEA-CERN collaboration where

– CSIC/CIEMAT would manufacture the coils,

– CEA would integrate the cold mass,

– CERN would upgrade the FRESCA systems and cold

test the model magnet.