NED Status Report

1
NED Status Report
Andries den Ouden University of Twente CARE-DB
Paris 17 April 2007
2
CARE/NED JRA

• Following the 2003 EU peer review, the scope of
  the NED program was revised to focus on Nb3Sn
  conductor and insulation development.
• The NED JRA is presently articulated around four
  Work Packages and one Working Group
• 1 Management Communication (MC),
• 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.
• It involves 7 institutes (8 laboratories)
• Total budget 2 M EU grant 979 k (over 3
  years).

3
NED/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 Nb3Sn
  conductor insulation to investigate temperature
  margins of superconducting magnet coils under
  heavy beam losses
• (CEA and WUT Task Leader B. Baudouy, CEA),
• quench computation, so as to study the
  protection of NED-like, high-field Nb3Sn
  accelerator magnets
• (INFN-Mi Task Leader G. Volpini).

4
NED Heat Transfer Task (1/4)

• The first part of the Heat Transfer Task was to
  design and build a new He-II, double-bath
  cryostat.
• The cryostat was built by Kriosystem in Poland
  under the supervision of Wroclaw University
  according to specifications written by CEA.
• The cryostat was delivered to CEA on 20 Sept.
  2005 and was commissioned in September 2006.
• It is now routinely operated for various types
  of heat transfer measurements.

Views of NED cryostat (Courtesy M. Chorowski,
WUT)
5
NED Heat Transfer Task (2/4)

• Since initial commissioning, it was verified
  that He-II bath temperature can be stabilized to
  1 mK level over one hour.

First thermal stability tests on NED
cryostat (Courtesy B. Baudouy, CEA)
6
NED Heat Transfer Task (3/4)

• First experiment was to re-test at CERN CEA an
  8-year old sample (of 5 pseudo insulated cables)
  that had been left untouched in its holder.

• Measurements at CERN CEA are in fair
  agreement, but there appears a significant
  improvement with respect to 1998 measurements
  (under investigation).

(Courtesy B. Baudouy, CEA)
7
NED Heat Transfer Task (4/4)

• Program calls now for the study and
  characterization of various types of insulation
  schemes considered for NED, using two sample
  configurations.

1-D drum sample
Compressed cable stack sample
(Courtesy B. Baudouy, CEA)
8
NED Heat Transfer Task (5/4)
Compressed cable stack sample wrapped with
ceramic insulation
First results show large transparency of ceramic
insulation for superfluid helium, but results
need verification
9
Complementary TSQP Efforts (1/3)

• Since the start of NED, three complementary
  efforts have been launched at CERN
• Analysis of available LHC magnet test data at
  high ramp rate to determine how well the CEA
  heat-transfer measurements correlate with actual
  magnet data (interactions with US-LARP),
• In-situ heat transfer measurements on LHC magnet
  coil sections to compare with CEA tests
  (interactions with US-LARP),
• Review of magnet cooling modes to estimate, on
  the cryogenics system point of view, what are the
  limitations on power extraction and to provide
  guidance on how to improve cooling of magnet
  coils
• (preliminary conclusions indicates that NED-like
  magnets may have to be operated in superfluid
  helium).

10
Complementary TSQP Efforts (2/3)

• D. Richter (CERN) has reanalyzed ramp-rate data
  from a series of short LHC dipole magnet models
  to extract an effective heat transfer coefficient
  from heated coil to superfluid helium.

• The results are in agreement with a similar
  analysis performed on an LHC IR quadrupole magnet
  model at Fermilab and compare favorably with
  measurements performed at CEA more than 10 years
  ago (on samples relying on similar insulation
  scheme) providing that the heat transfer only
  occur on one coil side).

Comparison of effective heat transfer
coefficients (Courtesy D. Richter, CERN)
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Complementary TSQP Efforts (3/3)

• D. Richter also performed in situ measurements
  on a coil section cut from an LHC dipole magnet
  coil taken out of production line.
• He relied on interstrand resistances to heat up
  the conductors and thermo couples to measure
  their temperatures.
• The measured heat transfer coefficient is 1.4 to
  1.7 times higher than the one measured at CEA
  more investigations are needed.

(Courtesy D. Richter, CERN)
12
NED Quench Computation Task

• Task was completed in early 2006 and a final
  report has been issued.
• Computations have been carried out for 1-m, 5-m,
  and 10-m long, 88-mm-aperture cos?, layer design
  and 5-m-long, 160-mm-aperture, cos?, slot
  design.
• Both designs can be protected, using active
  quench protection heaters.

Simulation results for 10-m-long model (Courtesy
M. Sorbi, INFN-Mi)
13
NED/CD Work Package

• The CD Work Package includes two main Tasks
• conductor development
• (two industrial contracts under CERN supervision
  Alstom/MSA, France and SMI, The Netherlands Task
  Leader L. Oberli),
• conductor characterization
• (CEA, INFN-Ge, INFN-Mi, and TEU Task Leader A.
  den Ouden, TEU),
• It is the core of the Program and absorbs 70
  of the EU funding.
• It is complemented by two extensions of scope
• FE wire model development to simulate cabling
  effects
• (INFN-Ge CERN Task Leader S. Farinon,
  INFN-Ge),
• heat treatment study (CERN Task Leader C.
  Scheuerlein).

14
NED Conductor Development (1/2)

• The ambitious NED conductor specifications were
  derived by CERN and are aimed at manufacturing an
  88-mm-aperture, 13-to-14-T bore field (15-T
  conductor peak field) dipole magnet model.
• Salient NED wire parameters (compared to ITER
  and LARP) are
• diameter 1.250 mm (0.81/0.7 mm)
• eff. filament diameter lt 50 mm (lt 70 ?m)
• Cu-to-non-Cu ratio 1.25 0.10 (1)
• non-Cu JC _at_4.2 K 12 T 3000 A/mm2 (gt 2400
  A/mm2)
• IC _at_4.2 K 12 T 1636 A (200 A, gt 500 A)
• RRR (after HT) gt 200 (gt 100)
• billet weight gt 50 kg

15
NED Conductor Development (2/2)

• Both manufacturers have achieved great progress.
• Final production is expected next Summer (SMI) /
  Autumn (Alstom)
• (Note we have a new Alstom/MSA wire under
  evaluation).

SMI/NED (near final design) 1.26 mm 288 x 50 ?m
tube 1400 A (2500 A/mm2) _at_4.2 K 12T
Alstom/NED (workability studies) 1.25 mm 78 x
85 ?m sub-element 740 A (1500 A/mm2) _at_4.2 K
12T
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NED Conductor Characterization (1/2)

• NED conductors are characterized by performing
  critical current and magnetization measurements
  on virgin, rolled-down and extracted wires.
• Critical current measurements represent a real
  challenge, given the expected performances (e.g.,
  1600 A at 4.2 K and 12 T on a 1.25-mm-Ø wire,
  compared to 200 A presently achieved on 0.8-mm-Ø
  ITER wires).
• Magnetization measurements are performed under
  the supervision of INFN-Ge using a SQUID, a
  Vibrating Sample Magnetometer (VSM) and an AC
  susceptibility magnetometer as a function of
• field (to assess effective filament diameter and
  flux jumps),
• temperature (to study the nature and size of the
  various superconducting phases).

17
NED Conductor Characterization (2/2)

• The NED/SMI wire exhibit limited flux jumps and
  effective filament diameters conformed to
  expectations.

• Shielded volumes derived from m(T)

øNb 55 ?m øNb3Sn 44 ?m
(Courtesy M. Greco, INFN-Ge)
18
FE Wire Model (1/2)

• To better understand cabling degradation and the
  sensitivity of un-reacted wires to transverse
  loading, INFN-Mi and CERN have launched an effort
  aimed at developing a comprehensive FE model.

• Such model requires a detailed knowledge of the
  mechanical properties of the materials making up
  the wire (in the cold-worked state where they end
  up at the end of drawing).
• These properties were assessed through extensive
  micro- and nano-hardness measurements.

Microhardness measurements on X-cut of
internal-tin wire (courtesy C. Scheuerlein,
CERN)
Nanohardness measurements on longitudinal cut of
internal wire (courtesy S. Sgobba, CERN)
19
FE Wire Model (2/2)

• The FE model itself is based on ANSYS and was
  developed by S. Farinon (INFN-Ge) it
  provides a unique tool to compare billet layouts.
  

Side-by side comparison of computed and observed
deformations of un-reacted internal tin (left)
and PIT (right) wires (Courtesy S. Farinon,
INFN-Ge)
20
Heat Treatment Study (1/2)

• C. Scheuerlein (CERN) has undertaken
  investigating the influence of heat treatment
  parameters using various techniques (from
  micrographs to synchrotron tomography and
  diffraction at ESRF).

6 C h-1 to 580 C
gt100 C h-1 to 580 C
Influence of temperature ramp rate on void
formations in an internal tin wire (Courtesy C.
Scheuerlein, CERN)
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Heat Treatment Study (2/2)
Void formation observed during in-situ heat
treatment of an internal tin wire (60 C h-1 2
h _at_200 C, 5 h _at_40 C and 2 h _at_540 C) (Courtesy
C. Scheuerlein, CERN)
22
Heat Treatment Study (3/2)
Phase transformations during the reaction HT of
PIT Nb3Sn strands studiedwith hard X-rays (88
keV) at ESRF
(Courtesy C. Scheuerlein, CERN)
23
NED/IDI Work Package (1/2)

• The IDI Work Package includes two main Tasks
• studies on conventional insulation systems
  relying on ceramic or glass fiber tape and
  vacuum-impregnation by epoxy resin
• (CCLRC/RAL Task Leader S. Canfer),
• studies on innovative insulation systems
  relying on pre-impregnated fiber tapes and
  eliminating the need for a vacuum impregnation
• (CEA Task Leader F. Rondeaux).

24
NED/IDI Work Package (2/2)

• CCLRC/RAL is evaluating a polyimide-sized glass
  fiber tape that is able to sustain the required
  Nb3Sn heat treatment without degradation and
  which seems a promising solution to conventional
  insulation.
• The Innovative Insulation Task is built upon an
  ongoing RD program at CEA which has demonstrated
  the feasibility of such a system (2 patents) the
  efforts are now concentrated on characterizing
  and improving the mechanical properties of the
  insulation.

Polyimide-sized S2 glass fiber tape (Courtesy S.
Canfer, CCLRC/RAL)
Heat-treated conductor stack with CEA innovative
insulation (Courtesy F. Rondeaux P. Fourcade,
CEA)
25
NED/MDO Working Group (1/4)

• The Magnet Design and Optimization (MDO) Working
  Group is made up of representatives from CCLRC,
  CEA, CERN and CIEMAT(Chairman F. Toral,
  CIEMAT).
• The Working Group has completed its comparison
  of selected 2D magnetic configurations.
• In parallel, CERN has completed its optimization
  of 2D 88-mm-aperture, cos?, layer magnetic design
  (Reference Design V2) and CCLRC/RAL has
  undertaken a 2D mechanical design.

26
NED/MDO Working Group (2/4)
NED Magnet Zoo (Courtesy F. Toral, CIEMAT)
27
NED/MDO Working Group (3/4)

• CERN has completed its 2D electromagnetic
  optimization of the baseline, 88-mm-aperture,
  cos? layer design with respect to
• conductor geometry,
• iron shape (to reduce saturation effects),
• ferromagnetic shims (to compensate magnetization
  effects).

(Courtesy N. Schwerg, CERN)
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NED/MDO Working Group (4/4)

• CCLRC/RAL is pursuing its development of a
  comprehensive (ANSYS-based) mechanical model of
  baseline, 88-mm-aperture, cos? layer design
  throughout the various steps of manufacturing,
  cooldown and energization.

(Courtesy P. Loveridge, CCLRC/RAL)
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NED Next Step

• CCLRC/RAL, CEA and CERN have agreed to
  manufacture and test a series of LBNL-type Short
  Model Coils wound from NED-sub-cables so as to
  investigate
• cable and insulation performances in real coil
  environment,
• design limits for transverse and longitudinal
  loads.
• First results expected by the end of 2007
  (interactions with US-LARP).

30 cm
(Courtesy H. Félice, CEA)
(Courtesy P. Ferracin, LBNL)
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Longer Term Perspectives (1/2)

• The ultimate goal of NED was to build a
  88-mm-aperture, 15-T-conductor-peakfield dipole
  magnet model the proposed magnet model served
  two main purposes

• studying the feasibility of LHC IR upgrade
  scenarios where beam-separation dipole magnets
  are localized ahead of final-focusing quadrupole
  magnets,

• upgrade of CERN MFRESCA cable test facility (now
  limited to 10 T) to offer unique services to the
  applied superconductivity community.

• Also, it was complementary to the US-LHC
  Accelerator Research Program (LARP), whose
  primary focus is on quadrupole magnets.

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Longer Term Perspectives (2/2)

• Funding for NED magnet model awaits CERN
  councils decision on the so-called white paper
  proposal, established by the CERN Director
  General, which requests an additional 240 MCH to
  support various types of RD efforts over the
  2008-2010 period (including magnet RD for LHC
  upgrade).
• If the white paper proposal is delayed and/or
  truncated, the plan is to submit another proposal
  to FP7 (funding will not be available before
  2009).

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Conclusion

• In spite of limited funding, significant
  progress has been achieved and most Tasks of the
  present program are expected to be completed by
  the Summer.
• A Short Model Coil program has been launched and
  should yield its first results before the end of
  the year.
• We are hopeful that the CERN council will enable
  the NED collaboration to move forward with the
  model magnet design and manufacturing.