Superconductivity Practical Days at CERN HTS Leads Superconductivity Practical Days at CERN 26th-27th 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 J.Fleiter, A.Ballarino

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

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 JUAS 2015 16/02/2015 J.Fleiter, A.Ballarino

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 JUAS 2015 16/02/2015 J.Fleiter, A.Ballarino

Definitions Superconductivity Superconductor Cryogenics “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 J.Fleiter, A.Ballarino

Main properties of superconductors For T<Tc Zero resistance Perfect conductors Exclusion of magnetic field Perfect diamagnets Zero resistance Onne’s measurement on mercury (1911) Meissner effect Discovered by Meissner and Oschenfeld (1933) Perfect conductivity + perfect diamagnetism = superconductors JUAS 2015 16/02/2015 J.Fleiter, A.Ballarino

Superconducting state if: Phase diagram of superconductors Critical temperature (Tc) Critical field (Hc) Critical current density (Jc) Superconducting state if: T<Tc H<Hc J<Jc JUAS 2015 16/02/2015 J.Fleiter, A.Ballarino

Various Superconducting materials Low Temperature Superconductors (LTS)Tc<39K High Temperature Superconductors (HTS) Tc>39K Cuprates Pure metals Alloys and Intermetallic alloys JUAS 2015 16/02/2015 J.Fleiter, A.Ballarino

Properties of HTS versus LTS Bc up to 30 T Tc up to 39 K HTS Bc up to 200 T Tc up to 120 K 7106 (A/cm2) Tc=110K Tc=10K Bc=15T Bc=100T JUAS 2015 16/02/2015 J.Fleiter, A.Ballarino

Superconductivity applications Generate high DC field: (MRI, NMR, particle Physics) Current limiters Electronics, detectors (SQUIDS) Power transmission Magnetic levitation (Maglev) Current leads RF cavities JUAS 2015 16/02/2015 J.Fleiter, A.Ballarino

Superconducting devices @CERN Superconductivity = a core technology of LHC LHC ring magnets (Nb-Ti): 1232 main dipoles: 8.3 T x 15 m 392 Main quadrupoles 223 T/m (7 T) x 8m Zoo of 7600 others LHC detector magnets (Nb-Ti ): ATLAS: Toroid 4 T, 25 x20 m CMS solenoid: 4 T, 12 x15 m LHC current leads (HTS BSCCO) ~1000, rated for I ϵ[0.6,13 kA] RF cavities (Nb coating) JUAS 2015 16/02/2015 J.Fleiter, A.Ballarino

Superconductors in form of tape or wire Superconductors @ CERN Only few superconducting materials could be used as superconductor for large scale application Low Temperature Superconductors: Nb-Ti (Tc=9K, Bc=15T) LHC machine Nb3Sn (Tc=18 K, Bc=30T) Hi Lumi-LHC (2017) MgB2 (Tc=39K, Bc=30T) Hi Lumi-LHC (2022) High Temperature Superconductors: Bi2Sr2Ca2Cu3O10+x(Tc=108 K, Bc>100 T) LHC machine Bi2Sr2CaCu2O8+x(Tc=95 K, Bc>100 T) High energy-LHC (>2030) YBa2Cu3O7-x (Tc=93K, Bc>100 T) High energy-LHC (>2030) Superconductors in form of tape or wire used to make cables JUAS 2015 16/02/2015 J.Fleiter, A.Ballarino

LTS => Liquid Helium HTS =>Liquid Helium or Liquid Nitrogen Superconductors needs Cryogens LTS => Liquid Helium HTS =>Liquid Helium or Liquid Nitrogen Saturated Vapor/liquid Triple point (K) Boiling point (1 atm) Critical Point Methane 90.7 111.6 190.5 Oxygen 54.4 90.2 154.6 Argon 83.8 87.3 150.9 Nitrogen 63.1 77.3 126.2 Neon 24.6 27.1 44.4 Hydrogen 13.8 20.4 33.2 Helium -point 4.2 5.2 JUAS 2015 16/02/2015 J.Fleiter, A.Ballarino

Superconductivity Practical Days at CERN 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 ……… JUAS 2015 16/02/2015 J.Fleiter, A.Ballarino

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

Superconductors you will use for the experiments at CERN: 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..) HTS SmCo 4 mm 0.2 mm JUAS 2015 16/02/2015 J.Fleiter, A.Ballarino

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

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

Zero resistance experiment Zero resistance DC experiment 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. A see-through glass walled dewar is used for the LN2. Ag(293 K)1.46∙10-6 Ω∙m Ag(77 K) 0.2∙ Ag(293 K) HTS:BSCCO 2223 multi-filamentary tape in silver alloy matrix. JUAS 2015 16/02/2015 J.Fleiter, A.Ballarino Zero resistance experiment

Critical current experiment DC Critical current experiment HTS Leads Critical current (Ic): current at which a specified electric field criterion Ec, or resistivity criterion c is achieved in the specimen. Losses through a Type II superconductors (Hc1<H<Hc2) depend on the sample geometry and on the vortex pinning. VIn n=n-value N reflects the abruptness of the transition from superconducting to normal state H=const T=const JUAS 2015 16/02/2015 J.Fleiter, A.Ballarino Critical current experiment

We are looking forward to working with you at CERN ! JUAS 2015 16/02/2015 J.Fleiter, A.Ballarino