Polyhelix ECR & high field magnet development at LNCMI: an emergent synergy F. Debray, CNRS, LNCMI-Grenoble

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1 Polyhelix ECR & high field magnet development at LNCMI: an emergent synergy F. Debray, CNRS, LNCMI-Grenoble HIGH FIELD? In 2009, dc magnetic fields up to 35 T are available to the scientific community in 3 laboratories (Grenoble, Nijmegen and Tsukuba) and 45 T in Tallahassee in Florida.

2 High field labs in Europe Toward a European Magnetic Field Laboratory Nijmegen (B dc) Dresden (B pulsed) Grenoble (B dc) Toulouse (B pulsed) 1 st January 2009 : fusion between Grenoble and Toulouse (LNCMI)

3 United States High field labs in the world dc field pulsed field Japan China Tallahassee (dc), Los Alamos (pulsed) Gainesville (NMR) Tsukuba, Sendaï Hefei (dc), Wuhan (pulsed) 2009 : Magnet Technology conference ( Hefei ) 2011 : Magnet Technology conference ( Marseille/Cadarache )

4 Magnetic field (State of the Art for solenoids) S U P E R Field Sol. config. Material 12 T NbTi 22 T Nb 3 Sn IRM ( each year) 1232 dipoles for the LHC (8.4 tesla / 1.8 K) (next test in Nov. 2009) High field MRI Iseult CEA/Bruker : 1 m diam. /360 MJ/ teslas NMR for Physics and Biology ITER : Development of Nb 3 Sn cables COPPER ~ 35 T Copper alloy In 3 laboratories Nijmegen 20 MW (33T), Grenoble 24 MW (35 T), Tallahassee 48 MW (35 T) Inter helix cooling Inter pitch cooling J X Bz Bitter ~ 1000 electric contacts under variable pressure with B J X Bz

5 State of the Art for high field magnets Longitudinally cooled helices 25 T Radially cooled helices High field inserts (under development) Bitter 10 T

6 «Classical» sheme for resistive magnets (LNCMI, Nijmegen, Tallahasse, Tsukuba) 15 KV cells 15KV/400V Transformers Thyristors Bridge Polariry inversor Bus bars Switches Cables Magnets DTA1 TRA1 AC DTB1 DC DTA2 TRB1 TRA2 AC DTB2 TRB2 DC 70 A / cm2 700 A / cm A / cm2 At LNCMI : 4 * I = A, U = 400 V 4 * 6.5 MW For EHMFL project 4 * I = A, U = 500 V 4 * 9 MW

7 20 T /160 mm 35 T 30T/50 mm 25 T 13th October 2009 : special ESRF tuesday event

8 DC Magnetic field (solenoid), State of the Art H Y B R I D S 35 to 45 T NbTi, Nb 3 Sn + Copper alloys Existing : Tsukuba, Japan 35 T = 14 T (Nb3Sn) + 21 T (~14 MW) Tallahassee, US 45 T = 11 T (Nb3Sn) + 34 T (~30 MW) ~ foreseen for : Grenoble, France 42 T = 8 T (NbTi) + 34 T (24 MW) Nijmegen, the Netherlands 42 T = 12 T (Nb 3 Sn) + 30 T (20 MW) Hefei, China 40 T = 11 T (Nb 3 Sn) + 29 T (20 MW) Tallahassee, United States 36 T = 14 T (Nb 3 Sn) + 22 T (12 MW) Tallahassee : 36/40 T (2013) 14 T Nb3Sn 22 T / 12 MW Grenoble : 40/42 T (2013)( 8.5 T NbTi 34 T / 24 MW N E X T 30 to 50 T High Tc Superc. YBaCuO BISCO : R&D and first prototypes of HTc magnets : SMES : NEXANS/CNRS : 1MJ / 5,5 T magnets in 20 T : NEXANS/CNRS/CEA FZK, Tallahassee, EUCARD S T E P with less power MgB2 & Copper alloys : compact magnet suitable for EHMFL, Split magnet with enhanced cooling (EHMFL, NHMFL) Toward 30 T superconducting magnet (EHMFL, NHMFL)

9 4000 h of high field per year User facility 24 MW of electrical power Development of the facility 35 T resistive magnets 42 T hybrid development

10 New requests came since 2006 High fields for Neutrons and X Ray Dream : 30 T in split geometry ECR : from 28 GHz 60 GHz With ILL and ESRF With LPSC Common feature : highly constrained geometries very high current densities

11 Split magnet (State of the Art) B solenoid config. Material B Super 12 T NbTi 22 T Nb 3 Sn Copper ~ 35 T Copper alloys Nijmegen Grenoble, Tallahassee Consequences B goes down with the gap size Attractives forces : (J0XBr) ~ 20 MPA Limited acces to the centre: ~ 30 % B losses as compared to solenoids State of the Art for split magnet 15 T Split magnet Nb3Sn

12 Choice of the technology for split and ECR magnet Solenoidal magnet with longitudinal cooling B max for a given power : smooth change of current density along the axis Cooling along the cylindrical faces B Water flow Channel thickness ~ 1 mm, V= 30 m/s, P =20 Bar Heat flux = 3 MW / m 2 Heat transfer coefficient h ~10 5 W/m 2 /K Heat conduction length = helix thickness Split magnet/ecr magnet with longitudinal cooling B max for a given power : rapid change of current density along the axis (~factor 10) Main hydraulic path is perpendicular to the split plane Split/ECR magnet with radial cooling Cooling is performed between each turn of the winding. Main hydraulic path is parallel to the split plane The magnet is thermally limited near the mid plane High flow rates and electric current have to pass through the mid plane No versability for the mid plane conception to fit the users needs. Higher cooling capacity No hydraulics and electrics constaints in the mid plane region High versability for the mid plane conception to fit the users needs. 13th October 2009 : special ESRF tuesday event

13 Cooling Critical points : Split compact Materials magnet for ILL/ESRF 600 Heat flux (MW/m 2 ) Existing high field magnets Yield Strength (MPa) run = 1 day 1 run = 1 month?? Duration of the heat flux (s) Electrical 20 C (MS/m) Experimental studies of heat transfer in extreme condition (LEGI collaboration, Euromagnet program Test and development of new alloys (with LNCMI-Toulouse and suppliers) 13th October 2009 : special ESRF tuesday event

14 Radially cooled split coil Radial Cooling Magnets in 2 independent parts «large» diffraction angle (mid plane free of hydraulics and electricity) High h(w/m2/k) on inner windings compact magnet 13th October 2009 : special ESRF tuesday event

15 Highest constrains : Attracting forces (resp. Repulsing) between helices z hoop stres J s J θ B z θ Hoop stress (JOXBz) ~500 MPA Compressive stress (JΟXBr) ~50 MPA 13th October 2009 : special ESRF tuesday event

16 F 2*10 MN Split Magnet : Results of the Esrf Up WP12 Other possibilities do exist as the mid plane interface is independent on the magnet 13th October 2009 : special ESRF tuesday event

17 Choice of radially cooled magnet : Compactness of the magnet High Gradient with acceptable electrical power Structural mechanics easier to conceive

18 Conclusions Strong undergoing development of radially cooled magnets for constrained geometry 2010 : First test of prototype for ECR, High field radially cooled insert 2011/2012 Prototype of split magnet These projects benefit from each other giving a safety margin to the R&D process. Thank you for your attention!!