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Next European Dipole (NED)
Status Report
Arnaud Devred
CEA/DSM/DAPNIA/SACM & CERN/AT/MAS
on behalf of the NED Collaboration
HHH General Meeting
CERN
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
3
4
5
Thermal Studies and Quench Protection (TSQP),
Conductor Development (CD),
Insulation Development and Implementation (IDI),
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)
GHe
LHe
• CEA has designed a new
Pumping
pressurized, He-II, double-bath
Cryogenic
vessel
Heat exchanger
piping
Insert
cryostat.
• The cryostat is being
manufactured under WUT
supervision and is scheduled for
delivery to Saclay in the first
Heat
exchanger
Radiation
shields
Expansion
valve
He I
He IIp
Vacuum
container
Experimental
volume
He IIs
quarter of 2005.
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.
Drum Sample
(courtesy B. Baudouy, CEA)
Stack Sample
(courtesy N. Kimura, KEK)
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.
7.E+16
U (A^2 s m^-4)
6.E+16
5.E+16
4.E+16
3.E+16
2.E+16
1.E+16
0.E+00
0
100
200
Te m pe rature (K)
Comparison of MIITs
computations for impregnated
NED cables relying on
different data sources
(courtesy M. Sorbi, INFN-Mi)
300
Quench Protection Task (2/2)
• INFN-Mi is now undertaking systematic quench protection studies,
starting from the 88-mm-aperture, cosq, layer design chosen as
300
600
250
500
200
Layer1
Layer2
150
Layer 1 unif.
100
Layer2 unif.
50
0
0
10
20
Rd (ohm x 1E-3)
30
40
Max voltage (V)
Hot spot Temp. (K)
reference for NED.
400
300
Hot-spot
temperature
200
computations using the
100
QLASA code for the NED, 880
mm-aperture,
cosq, layer
0
10
20
30
baseline
design
Rd (ohm x 1E-3)
(courtesy M. Sorbi,
INFN-Mi)
40
TSQP Planning
WBS
#
2.1
2.2
2.2.1
2.2.2
2.2.3
2.2.4
2.2.5
2.3
Title
Original
begin date
(Annex 1)
Original
end d ate
(Annex 1)
Estimated
Status
Revised
end d ate
TSQP WP
Coordination
Heat Transfer
Measurements
Specifi cations
Cryos tat design and
manu facturing
Heat exchang er
manu facturing
Facilit y integration
and commi ssioning
Measurements and
data ana lysis
Quench protection
computation
• Collaboration between
CEA and WUT is off to a
good start –enthusiasm
1 Janua ry
2004
1 April
2004
1 April
2004
1 Janua ry
2005
1 April
2005
1 April
2004
31 March
2004
31 Dec.
2004
31 Dec.
2004
31 March
2005
31 Dec.
2006
30 June
2005
Completed
8 June
2004
Ongo ing
On time
Ongo ing
On time
Not started
-
Not started
-
Ongo ing
On time
of team compensates lack
of human resources.
• All tasks are 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 cosq, 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.
2.357302 MN/m
3.401580 MN/m
1.721069 MN/m
1.104555 MN/m
3.913917 MN/m
1.443344 MN/m
1.366123 MN/m
2.636726 MN/m
0.522062 MN/m
1.759376 MN/m
1.599814 MN/m
88-mm-aperture,
layer type
88-mm-aperture, slot type
(courtesy D. Leroy and O. Vincent-Viry)
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, cosq, 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 mm,
– 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, cosq
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).
• The measurements will be
4.2 K, // applied field
performed as a function of field to
1.5
VSM
SQUID
appreciate the effective filament
Magnetic Moment (emu)
1
diameter and the presence or not of
0.5
flux jumps.
0
-0.5
-1
-1.5
-4
-3
-2
-1
0
B (T)
1
2
3
4
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)
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 unreacted Nb in PIT wires.
0.0005
T Nb Sn=17.4 K
c
3
magnetic moment (emu)
0.0000
-0.0005
-0.0010
T Nb=9.2 K
c
-0.0015
Nb Sn shield: 0.00146 emu
3
-0.0020
FNb=65
mm
-0.0025
total shield : 0.003 emu
-0.0030
4
6
8
10
12
T (K)
14
16
(courtesy C. Ferdeghini,
INFM/Genova)
18
20
(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
Original
begin date
(Annex 1)
Original
end d ate
(Annex 1)
1 Janua ry
2004
1 April
2004
31 Dec.
2004
30 June
2004
1 July
2004
30 June
2006
1 July
2004
1 Janua ry
2005
1 July
2005
1 July
2005
1 July
2005
30 June
2006
30 June
2005
30 June
2006
30 June
2006
30 June
2006
1 July
2005
30 June
2006
3.6
Cable develop ment
and manuf acturing
1 July
2005
3.7
Cable
cha racterization
1 October
2005
WBS
#
Title
3.1
CD WP Coordination
3.2
Prelimi nary design
3.3
Condu ctor
specification s
3.4
Wir e development
3.5
Wir e char acterization
3.5.1
3.5.2
3.5.3
3.5.4
3.5.5
Defi niti on o f
procedures
Ic measurements at
CEA
Ic measurements at
INFN/Mi
Ic measurements at
TEU
Magne tization
measurements at
INFN/Ge
Estimated
Status
Revised end
date
• Start date of 3.4
delayed by 3 months
90%
complete
On time
Completed
On time
Started
30
September
2006
due to longer contract
negotiations than
anticipated.
• End date of 3.4 delayed
Ongo ing
On time
accordingly.
31 October
2006
31 October
2006
31 October
2006
• End date of 3.5 delayed
Started
31 October
2006
3.5 not moved due to
31 Dec.
2006
Not started
15
December
2006
31 Dec.
2006
Not started
-
Ongo ing
Started
Started
Started
to match that of 3.4.
• End dates of 3.6 and
some built-in slack in
initial program.
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
Example of Double Cantilever
Beam(DCB) test sample
(courtesy S. Canfer, CCLRC)
Precrack
(release
film)
Crack growth
from test
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
WBS
#
Title
Original
begin date
(Annex 1)
Original
end d ate
(Annex 1)
1 April
2004
30 June
2004
1 October
2004
1 Janua ry
2005
1 July
2005
30 Sept.
2004
30
October
2004
31 Dec.
2004
30 Sept.
2005
30 June
2006
1 July
2004
1 July
2004
31 Dec.
2004
30 June
2005
4.1
IDI WP Coordination
4.2
Specifi cation d rafti ng
4.3
Conv entional
Insu lation
4.3.1
Literature survey
1 July
2004
4.3.2
Tooling preparation
1 October
2004
4.3.3
Componen t supp ly
4.3.4
Iterative tests
4.3.5
Irradiation tests
4.4
Innova tive Insu la tion
4.4.1
Tape weaving trial
4.4.2
Characterization tests
• Scope of 4.3.5 has
Estimated
Status
Revised end
date
Completed
22 July 2004
Completed
On time
Ongo ing
30
November
2005
Ongo ing
On time
Not started
Not started
Not started
Not started
31 Dec.
2005
30 June
2006
31 Dec.
2005
30 June
2006
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.
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, cosq, 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
Aperture
Superconductor Jc
Cu to non-Cu ratio
Operating margin
Filling factor of cable
Insulation thickness
Cabling degradation
X-section multipoles
Overall coil length
Peak stress
Max coil deformation
15
88-130-160
3000
1500
1 to 2
10 to 20
87
0.2
10
A few10-4
1.3
150
<0.05
Peak temperature
Peak voltage to ground
Peak inter-turn voltage
300
1000
100
T
mm
A/mm2 @ 4.2K and 12 T
A/mm2 @ 4.2K and 15 T
%
%
mm per conductor face
%
@ 2*aperture/3
M
MPa
mm (due to Lorentz
forces)
K (quench)
V (quench)
V (quench)
MDO Terms of Comparison
1. Magnetic field:
a. Central field
b. Peak field
c. Nominal current
d. Field quality
e. Tunability
f. Magnetic length compared to overall length
g. Operating margin
2. Mechanical design:
a. Change of pre-stress during cooling down
b. Peak stress
c. Lorentz forces
3. Quench:
a. Self-inductance
b. Stored magnetic energy
c. Peak voltage and temperature
4. Fabrication:
a. Sensitivity to manufacturing tolerance
b. Manufacturability
c. Coil end complexity
d. Minimum bending radius (parallel and perpendicular)
e. Superconductor volume efficiency
f. Twin/single aperture and minimum distance
g. Cost
h. 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.