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.