J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th NED heat transfer program at CEA NED heat transfer program at CEA Jaroslaw Polinski, Bertrand Baudouy CEA/ DAPNIA/SACM

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Motivations of the program Cryostat NED Conventional insulation (Kapton) – Saclay sample Ceramic (innovative) insulation – KEK sample RAL conventional insulation – drum method Technical solutions investigation Conclusions Contest

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Motivations of the program Cryostat NED Conventional insulation (Kapton) – Saclay sample Ceramic (innovative) insulation – KEK sample RAL conventional insulation – drum method Technical solutions investigation Conclusions Contest

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Operation of the SC accelerators is connected with energy deposition in SC cables due beam losses –Current (NbTi) LHC – e ≈ 0.4 – 0.6 W/m, 10 – 15mW/cm 3 –Future (Nb 3 Sn) LHC – e ≈ 2 – 3 W/m, 50 – 80mW/cm 3 –Max temperature of the SC cable ≈ 3.3K Motivations of the program

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Motivations of the program B. Baudouy et al., Heat transfer in electrical insulation of LHC cables cooled with superfluid helium, Cryogenics 39, Elsevier 1999 Exemplary experimental results for different configuration of the polyimide (Kapton) insulation LHC NbTi

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Operation of the SC accelerators is connected with energy deposition in SC cables due beam losses –Current (NbTi) LHC – e ≈ 0.4 – 0.6 W/m, 10 – 15mW/cm 3 –Future (Nb 3 Sn) LHC – e ≈ 2 – 3 W/m, 50 – 80mW/cm 3 –Max temperature of the SC cable ≈ 3.3K Nb 3 Sn technology need the thermal treatment over 600 o C –Polyimide ( Kapton) insulation operation temperature > 400 o C Motivations of the program NEW GENERATION MAGNETS CALL FOR NEW MATERIALS FOR SC CABLES ELECTRICAL INSULATIONS

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Motivations of the program Cryostat NED Conventional insulation (Kapton) – Saclay sample Ceramic (innovative) insulation – KEK sample RAL conventional insulation – drum method Technical solutions investigation Conclusions Contest

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Cryostat NED Cryostat scheme (cooperation with WUT) Claudet bath principle Helium phase diagram

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Cryostat NED Experimental setup at CEA Saclay

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Cryostat NED Performance of the NED cryostat

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Motivations of the program Cryostat NED Conventional insulation (Kapton) – Saclay sample Ceramic (innovative) insulation – KEK sample RAL conventional insulation – drum method Technical solutions investigation Conclusions Contest

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Insulation description 1st layer: Kapton 200 HN (50 μm x 11 mm) in 2 wrappings (no overlap) 2nd layer: Kapton 270 LCI (71 μ m x 11 mm) with a 2 mm gap Thermally treatment at 170 o C for polymerisation Conventional Kapton insulation

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Dummy conductors Material: Stainless Steel Dimensions: 2.5mm x 17mm x 150mm (T x W x L) Central surface part machined to real cable geometry Allan Bradley temp. sensors placed in the quarter and half of the conductor length Conventional Kapton insulation

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Conventional Kapton insulation Tests conditions 5 conductors stack, 17 Tons on the samples as specified Temperature of the bath T b = 1.8K, 1.9K and 2.0K Only conductor III (central) heated Supplied current range: 0 – 10 Amps Dissipated heat range: 0 – ≈30 mW/cm 3 T measured at the centre of conductors II, III and IV

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Conventional Kapton insulation Saclay sample

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Test results – comparison with CERN results –Temperature of the heated conductor (conductor III) I II IV V III T III For Q=10 mW/cm 3 (NbTi) –  T≈50 mK For Q=50 mW/cm 3 (Nb 3 Sn) –  T≈2.2K !!! Conventional Kapton insulation

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th I II IV V III Typically temperature characteristic for conductors adjoining to heated conductor T b =2.0K Test results –Temperature of the conductors II and IV, adjoining to heated conductor T III =T T III <T T III >T T II T IV Exemplary modeling results Conventional Kapton insulation

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Motivations of the program Cryostat NED Conventional insulation (Kapton) – Saclay sample Ceramic (innovative) insulation – KEK sample RAL conventional insulation – drum method Technical solutions investigation Conclusions Contest

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Insulation material Mineral fibre tape vacuum impregnated with epoxy resin Treated for 50 hours at 666 o C at 10 MPa Single cable and sack of cables with ceramic insulation – photo F. Rondeaux Ceramic (innovative) insulation

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Dummy conductors Material: CuNi Dimensions: 1.9mm x 11mm x 150mm (T x W x L) Conductor fabricated in real cable technology CERNOX temp. sensors placed in the quarter of the length and in axis of the conductor Ceramic (innovative) insulation

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Ceramic (innovative) insulation Test condition 10 MPa on the samples as specified Temperature of the bath Tb= 1.8K, 1.9K and 2.0K All conductors heated Supplied current range: 0 – 10 Amps Dissipated heat range: 0 – ≈42 mW/cm 3 Temperature measured on the central conductor

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Ceramic (innovative) insulation KEK sample

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Test results For Q=10 mW/cm 3 (NbTi) –  Tmax<10 mK For Q=50 mW/cm 3 (Nb 3 Sn) –  T<35 mK !!! Ceramic (innovative) insulation

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Motivations of the program Cryostat NED Conventional insulation (Kapton) – Saclay sample Ceramic (innovative) insulation – KEK sample RAL conventional insulation – drum method Technical solutions investigation Conclusions Contest

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Construction of the drum test support Sample holder flange Support flange RAL insulation

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Drum setup –Theoretical Background of the Method (1/2) A – Active area of the heat transfer h k – Kapitza heat transfer coefficient λ – Thermal conductivity of the material l – material thickness R s – overall thermal resistance of the sample T i – temperature of the heated volume T 1 – temperature of the sample surfaces from the heated volume side T 2 – temperature of the sample surfaces from the constant T bath T b – temperature of the constant T bath TiTi T2T2 T1T1 TbTb QsQs A l Heated volume Constant T bath RAL insulation

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Drum setup –Theoretical Background of the Method (2/2) Since  T>>T b it can be assumed that: And finally overall thermal resistance of the sample: RAL insulation

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th RAL insulation material - fiberglass tape and epoxy resin Tested sheets Sheet surface photo RAL insulation

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Study of sheets surface area and thickness l h H Thickness determination Surface mathematical description H W Surface roughness tester result Surface Roughness Tester RAL insulation

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Tests conditions 4 sheets with different thicknesses 7 different temperatures of the bath from range: 1.55 K – 2.05 K Temperature of the inner volume: Tb – T Heat dissipated in inner volume: 0 – 0.8 W Range of  T accounted in computation process: 10 – 30 mK RAL insulation

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Test results and computation process, example for l =0.055 mm Evolution of the temperature difference across the sample with heat flux as a function of the bath temperature. where y = x RAL insulation

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Computation process RAL insulation

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Thermal conductivity, comparison with other materials RAL insulation

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Kapitza Resistance RAL insulation

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Motivations of the program Cryostat NED Conventional insulation (Kapton) – Saclay sample Ceramic (innovative) insulation – KEK sample RAL conventional insulation – drum method Technical solutions investigation Conclusions Contest

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Technical solutions investigation

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th kN ≈10 MPa Vacuum grease – thermal blockade G10 interlayer spacer 0.9 mm Spacer Thermal blockades of the one side of the conductors stack G10 interlayer spacer Technical solution investigation

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th T Test results Technical solution investigation

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Motivations of the program Cryostat NED Conventional insulation (Kapton) – Saclay sample Ceramic (innovative) insulation – KEK sample RAL conventional insulation – drum method Technical solution study Conclusions Contest

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Conclusion For Nb 3 Sn technology magnets beam losses heat generation in cables would be about 5 times higher then for NbTi technology Temperature margin as 2.2 K is expected when the LHC convectional electrical insulation is used to Nb 3 Sn cables Innovative ceramic insulation seems to be very good solution for future Nb 3 Sn magnets Thermal conductivity of the RAL insulation material is 5 times lower then Kapton with similar Kapitza resistance values – can be considered as new conventional insulation Yoke of magnet can strongly restrict heat transport from cables. Application of the G10 interlayer spacers improve this process.

J. Polinski, B. Baudouy -The NED heat transfer program at CEA CEA Saclay, January 11th Thank you for your attention