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Current leads for FAIR Cryogenic Expert Meeting 19./20. September 2007 Birgit Weckenmann

Current leads for FAIR Cryogenic Expert Meeting 19./20. September 2007 Birgit Weckenmann. Overview. 1. Design options for current leads 2. Current leads needed for FAIR 3. HTS leads in LHC at CERN 4. Cooling of HTS leads 5. Adaptation of CERN leads for FAIR. Conventional vs. HTS leads.

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Current leads for FAIR Cryogenic Expert Meeting 19./20. September 2007 Birgit Weckenmann

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  1. Current leads for FAIR Cryogenic Expert Meeting 19./20. September 2007 Birgit Weckenmann

  2. Overview 1. Design options for current leads 2. Current leads needed for FAIR 3. HTS leads in LHC at CERN 4. Cooling of HTS leads 5. Adaptation of CERN leads for FAIR

  3. Conventional vs. HTS leads HTS design Resistive design He gas 300K He gas 300K metal He gas 50K metal HTS LHe 4.4K LHe 4.4K + simple (standard) design + no quench protection + no additional instrumentation and control + reduction of cryogenic losses (~2.5 W/kA in DC operation)

  4. Low-current leads Conventional leads are chosen for all low current circuits with Imax≤ 300A Possible saving in cooling power by using HTS: 1500W => considering the large number of leads no benefit of that design Resistive leads are available in optimized design for several currents and can be purchased (Mark & Wedell, American Magnetics)

  5. High-current leads HTS leads are chosen for all high current circuits with Imax≥ 300A Saving in cooling power: 3700W => 87% reduction compared to resistive option => 15% of total cryogenic load of FAIR Adaptation of current lead design of LHC in collaboration with A. Ballarino (CERN)

  6. LHC current leads 13000A type: optimized for DC current of 13000A Resistive part: copper heat exchanger convection-cooled by forced flow of helium gas at 20K 6000A type: covering currents ranging from 3900A to 6900A HTS part: Stacks of BSCCO-2223 tapes soldered on SS tube conduction-cooled by liquid helium bath at 4.4K

  7. FAIR HTS leads Cooling conditions LHC: Cooling of resistive part with 20K Helium gas => HTS at 50K => m = 0.045 g/(s kA) FAIR: Cooling with gas at 50K results in a higher temperature of the HTS and a higher mass flow rate => HTS at 60K => m = 0.065 g/(s kA) (mass flow rate in pulsed operation will probably be lower)

  8. Adaptation of LHC design for FAIR leads Planned tests of CERN leads at ENEA (Italy) to prove the applicability of the LHC design to FAIR with 6000A type and 13000A type LHC leads provided by CERN 1. Test: Stable operation under changed cooling conditions => Cooling of the resistive part with 50K gas DC operation at all currents required by FAIR magnets 2. Test: Stable operation and quench behaviour in pulsed mode => 10 triangular cycles increasing ramp rate and current step by step Expected modifications: - Redesign of the heat exchanger (diameter) - Variation of HTS stacks (number)

  9. SIS100/SIS300 leads • One or more designs for FAIR leads? • Current range • SIS 100: 4600A to 6600A • SIS 300: 7900A to 9000A • Connection HTS to LTS • SIS 100: Nuclotron conductor • => adapter or change from bath • to indirect cooling (???) • SIS 300: Rutherford cable • => CERN design • => Two different designs may be reasonable

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