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Heat extraction through cable insulation and quench limits

Heat extraction through cable insulation and quench limits. Pier Paolo Granieri, Rob van Weelderen, Lina Hincapié (CERN) 2 nd Joint HiLumi LHC-LARP Annual Meeting INFN Frascati , 14-16 November 2012 (revised version 11/1/2013). Outline.

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Heat extraction through cable insulation and quench limits

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  1. Heat extraction through cable insulation and quench limits Pier Paolo Granieri, Rob van Weelderen, Lina Hincapié (CERN) 2nd Joint HiLumi LHC-LARP Annual Meeting INFN Frascati, 14-16 November 2012 (revised version 11/1/2013)

  2. Outline • Heat transfer through cable electrical insulation: evolution • Experimental method • setup description • results • Quench limits estimation • MQXF at 1.9 K bath temperature • vs. modeling results • vs. LHC magnets and MQXF at 4.2 K P.P. Granieri - Heat extraction and quench limits

  3. Heat transfer through cable electrical insulation: evolution P.P. Granieri - Heat extraction and quench limits

  4. Heat transfer through cable electrical insulation: evolution P.P. Granieri - Heat extraction and quench limits

  5. Heat transfer through cable electrical insulation: evolution P.P. Granieri - Heat extraction and quench limits

  6. Heat transfer through cable electrical insulation: evolution * * * * unpublishedmeasurementsfrom D. Richter (5 SCheatedcables, actual MQX cables) P.P. Granieri - Heat extraction and quench limits

  7. Heat transfer through cable electrical insulation: evolution * * * * unpublishedmeasurementsfrom D. Richter (5 SCheatedcables, actual MQX cables) P.P. Granieri - Heat extraction and quench limits

  8. Experimental method • Sample: - 150 mm long rectangular stack made of 6 alternating cables • Cable: - CuNi10 - LHC cables geometry, MB inner layer • T sensors: - AuFe0.07at%/Chromel differential thermocouples - in grooves in the central cable - installed before impregnation • Heating: - Joule heating along resistive strands - steady-state - different configurations (heated cables) P.P. Granieri - Heat extraction and quench limits

  9. Experimental method Q Q 1 2 Instrumented cable 3 4 5 6 • Insulation: - fiber glass sleeve - vacuum impregn. resin: CTD-101 - thickness: 150 µm • Cooling (transversal): - He II, 1.9 K - He I, 4.2 K • Pressure: 0 MPa P.P. Granieri - Heat extraction and quench limits

  10. Experimental results Tc (mid-plane, cable center) Tc (mid-plane, cableedge) Different position in the cable, Tbath, heating configuration P.P. Granieri - Heat extraction and quench limits

  11. Heat extraction from coil inner layer(cable center T) * 3 heatedcables P.P. Granieri - Heat extraction and quench limits

  12. Heat extraction from coil inner layer(cable center T) * 3 heatedcables P.P. Granieri - Heat extraction and quench limits

  13. Quench limit estimation 88 mW/cm3 80 mW/cm3 106 • MQXF • 150 mm bore (w/o µ-channels) • 1.9 K constant bath T • uniformheatdeposit 127 mW/cm3 Heatthat must be (uniformly) deposited in the cableuntil the cable center/edgereaches Tc: 247 mW/cm3 155 mW/cm3 39 143 mW/cm3 198 mW/cm3 188 P.P. Granieri - Heat extraction and quench limits

  14. Quench limit estimation 1.96 K 1.92 K • Mid-plane and pole cable temperature for heat deposit in nominal conditions (peak of 3.78 mW/cm3) 2.13 K 2.32 K Comparison tests vs. model *, independently carried out * previous talk from H. Allain P.P. Granieri - Heat extraction and quench limits

  15. Quench limit estimation Comparison at nominal conditions in mid-plane P.P. Granieri - Heat extraction and quench limits

  16. scaled to magnet geometry •  to beconfirmed by a • dedicated test Conclusions • Heat extraction through Nb3Sn insulation was measured • worse than through LHC Nb-Ti insulation below a ΔT of 1.8 K (in the cable center), since the He II contribution is missing • better than through Enhanced Nb-Ti insulation above a ΔT of 5.7 K (in the cable center), because kNb3Sn > KNb-Ti • 3.7 K • 6.4 K • Heat extraction from the cable allows a first estimate of the quench limit: • MQXF mid-plane cable is the most critical: 155 mW/cm3, vs. 4 mW/cm3 expected • MQXF-MQXC will have a quench limit 2 to 3 times those of MB-MQXA-MQXB Numerical model of the experimental tests Thermal measurement of a short model coil Perspectives P.P. Granieri - Heat extraction and quench limits

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