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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.