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J.Fleiter, A.Ballarino Superconductivity Practical Days at CERN 26 th -27 th February 2015 Jerome Fleiter and Amalia Ballarino With the collaboration for the practical exercises of: P. Denis, E. Seiler and J. Hurte JUAS 2015 16/02/2015 1

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J.Fleiter, A.Ballarino 10 to 12 participants Hands-on practical work in CERN laboratories Guided by experts When ? On the 26 th and 27 th of February Where ? In the Superconductor Laboratory, Building 163 JUAS 2015 16/02/2015 2 Program and Organization Main entrance B. 163

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JUAS 2015 16/02/2015 J.Fleiter, A.Ballarino 3 Practical Days at CERN (1/2) Visit of Superconductor Laboratory, Building 163 Test stations for the measurement of: Critical current of superconductors (strands and cables) at liquid He temperature (1.9 K and 4.2 K, up to 15 T and up to 35 kA); Magnetic properties of superconductors (magnetization curves) at variable temperatures and fields (VSM); Residual Resistivity Ratio, Resistivity as function of temperature; Cabling machine for accelerator Rutherford cables; Laboratory for analysis of superconductors; Nb-Ti, Nb3Sn, YBCO, BSCCO 2223 and MgB2 strands and cables Visit of Laboratory, SM 18 Test stations for magnets

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JUAS 2015 16/02/2015 J.Fleiter, A.Ballarino 4 Practical Days at CERN (2/2) What will you do ? Measure electrical, magnetic and thermal characteristics of superconducting samples with the purpose of understanding the fundamental characteristics of superconductors Superconductivity => Cryogenics

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J.Fleiter, A.Ballarino Definitions Superconductivity Superconductivity is a phenomenon occurring in certain materials at very low temperatures, (the Meissner effect) characterized by exactly zero electrical resistance and the exclusion of the interior magnetic field from Wikipedia Superconductor A conductor that exhibit superconducting properties. It is an assembly of low resistive metal and superconducting material. Cryogenics Cryogenic: for Greek kryos", which means cold or freezing, and "genes" meaning born or produced. In physics, cryogenics is the study of the production of very low eye temperature (below 150 C, 238 F or 123 K) and the behavior of materials at those temperatures from Wikipedia JUAS 2015 16/02/2015 5

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J.Fleiter, A.Ballarino Main properties of superconductors JUAS 2015 16/02/2015 6 Zero resistance Onnes measurement on mercury (1911) Meissner effect Discovered by Meissner and Oschenfeld (1933) For T

J.Fleiter, A.Ballarino Superconductors @ CERN Only few superconducting materials could be used as superconductor for large scale application Low Temperature Superconductors: Nb-Ti (T c =9K, B c =15T) LHC machine Nb 3 Sn (T c =18 K, B c =30T) Hi Lumi-LHC (2017) MgB 2 (T c =39K, B c =30T) Hi Lumi-LHC (2022) High Temperature Superconductors: Bi 2 Sr 2 Ca 2 Cu 3 O 10+x (T c =108 K, B c >100 T) LHC machine Bi 2 Sr 2 CaCu 2 O 8+x (T c =95 K, B c >100 T) High energy-LHC (>2030) YBa 2 Cu 3 O 7-x (T c =93K, B c >100 T) High energy-LHC (>2030) JUAS 2015 16/02/2015 12 Superconductors in form of tape or wire used to make cables

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J.Fleiter, A.Ballarino Superconductors needs Cryogens JUAS 2015 16/02/2015 13 Triple point (K) Boiling point (1 atm) (K) Critical Point (K) Methane90.7111.6190.5 Oxygen54.490.2154.6 Argon83.887.3150.9 Nitrogen63.177.3126.2 Neon24.627.144.4 Hydrogen13.820.433.2 Helium -point 4.25.2 Saturated Vapor/liquid LTS => Liquid Helium HTS =>Liquid Helium or Liquid Nitrogen

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J.Fleiter, A.Ballarino We will work with cryogenics and superconductivity to understand and verify the unique properties of superconductors YBCO 123 bulk BSCCO 2223 tape SmCo, NeFeB magnets Liquid nitrogen Levitation Flux pinning Zero resistance Jc,Tc,Hc Superconductivity Practical Days at CERN JUAS 2015 16/02/2015 14

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J.Fleiter, A.Ballarino 1.Levitation experiment 2.Flywheel demonstration 3.Critical temperature experiment 4.Zero resistance experiment 5.Critical current experiment 6.Resistive transition experiment Experiments JUAS 2015 16/02/2015 15 Experiments will be performed with HTS superconductors

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J.Fleiter, A.Ballarino HTS Liquid nitrogen Superconductivity Cryogenics Superconductors you will use for the experiments at CERN: YBCO 123 Melt Textured Bulk.Tc= 93 K BSCCO 2223 Tape Tc= 110 K You will use Nitrogen 78% of atmosphere Boiling point (1 atm): 77 K (-196 C) Colorless, odorless, non-toxic Dealing with LN2: safety first (skin burn, splashing..) JUAS 2015 16/02/201516 4 mm 0.2 mm HTS SmCo

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J.Fleiter, A.Ballarino Levitation experiment HTS SmCo HTS SmCo Appreciate the intensity of the max levitation force ! Understand the Meissner effect and flux pinning JUAS 2015 16/02/2015 17 Levitation experiment

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J.Fleiter, A.Ballarino Critical temperature experiment Measurement of critical temperature by using the Meissner effect. JUAS 2015 16/02/2015 18 The critical temperature is defined as the temperature measured on the superconductor when the permanent levitating on it comes to complete rest on the superconductors surface. Critical temperature experiment

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J.Fleiter, A.Ballarino A superconducting tape and a pure silver tape are connected in series, Measure the voltages (resistances) as the specimens are inserted into liquid nitrogen and cooled to 77 K. HTS:BSCCO 2223 multi-filamentary tape in silver alloy matrix. Zero resistance experiment A see-through glass walled dewar is used for the LN 2. Ag (293 K) 1.4610 -6 m Ag (77 K) 0.2 Ag (293 K) JUAS 2015 16/02/2015 19 Zero resistance DC experiment

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J.Fleiter, A.Ballarino Critical current experiment Critical current (I c ): current at which a specified electric field criterion E c, or resistivity criterion c is achieved in the specimen. Losses through a Type II superconductors (H c1