Superconducting characterization of prototype LTS samples

1. Superconducting characterization of prototype LTS samples Mattia Ortino, ESR13Atominstitut, TU Wien Vienna (AT) EASITrain – European Advanced Superconductivity Innovation and Training. This Marie Sklodowska-Curie Action (MSCA) Innovative Training Networks (ITN) has receivedfundingfrom the EuropeanUnion’s H2020 Framework Programme under Grant Agreement no. 764879

2. ESR13 project • APC • No APC ESR13 ESR13 Next steps Mattia Ortino

3. ESR13 project Project scope: ESR13 focuses on the superconducting and magnetic characterization of superconducting samples suitable for FCC-hh or FCC-driven applications 10T magnets (tapes) and FCC high current links (wires), Genova (IT) New “clusters” design wires, Moscow (RU) Artificial pinning centres (APC) doped wires, Columbus (USA) Mattia Ortino

4. ESR13 project Project structure: Tc measurements via AC susceptibility (SQUID) Bc2 and Jc via resistive and magneticmeasurements • Characterize the sample received from companies: Local properties via Scanning Hall Probe Microscopy (SHPM) • Collaborate with ESR12 (A.Moros, TU Wien), trying to relate these quantities with microstructural properties • Find relations with the manufacturing process and discuss with the sample suppliers about the possible improvements to be done Mattia Ortino

5. ESR13 project state of the art • APC • No APC ESR13 ESR13 Next steps Mattia Ortino

6. ESR13 Nb3Sn APC • Prerequisites: • Nb3Sn wiresarethebestcandidatesenvisagedforbuildingthe FCC-hh 16T dipole-magnets (cheaperthan HTS) • FCC-target performances (Jc = 1.5 kA/mm2at Bappl=16T and T=4.2 K)not yetreachedwithstate-of-art commercialwires • Technology (“Internal oxidation method”): • Oxygen selectively oxidizes Zr instead of Nb • ZrO2nanoparticles to be used as additional pinning centres (intra and inter-granular) • Nanoparticles should catalyse as well the A-15 grain size refinement, so that increasing Jc (Jc) ) Intra-granular ZrO2 particles Inter-granular ZrO2 particles Mattia Ortino

7. ESR13 Nb3Sn APC Grain size refinement Milestones • Characterization of prototype binary • (ZrO2 nanoparticles in A-15 phase) APC wires y (μm) 50 100 150 Higher Jc values than commercial wires Shifted/ peaks Low Bc2 Local inhomogeneities 0 20 40 60 80 100 120 x (μm) 36% 50% 80% Mattia Ortino

8. ESR13 Nb3Sn APC • Characterization of prototype ternary (ZrO2 nanoparticles + Ta in A-15 phase) APC wires • Magnetizationmeasurements: Tcandhysterisisloops • Samples-slices prepared down to polishing limits (40 to 10 μm) 0% 10% 50% 90% Offset (100%) Possible to perform Tc-radial analysis (radial inhomogeneities investigation) • SHPM Mattia Ortino

9. ESR13 project state of the art • APC • No APC ESR13 ESR13 Next steps Mattia Ortino

10. ESR13 no- APC T5 T2 T1 T3 T4 T8 T6 T7 • 8 samplesreiceved • Milestones: • AC magnetometry- in the range of temperature from 5 to 19 K; • Magnetic moment of wire sample as a function of temperature - M(T) curve for assessing Tc distribution. T3 T4 Cu Cu Sub-element with “clusters” Sub-element • Scanning Hall Probe Microscopy (SHPM) - in the range of temperature from 5 to 19 K; • Magnetization maps of individual sub-elements and clusters, Tc distribution within sub-elements and clusters and its variation between central and peripheral sub-elements Mattia Ortino

11. ESR13 no- APC: „clusters“ sample • SHPM : Meissner-state measurements • AC Magnetometry • SHPM : Remnant field-state measurements Remnant field scans used for local current evaluation In line with the state-of-art RRP wires (@ 10K, 0 T) Mattia Ortino

12. ESR13 no- APC: sample withoutclusters Sample withoutclusters (T4-distributed Nb) Line scansreveal an inter-subelementscoupling • SHPM : Meissner and remnant-field scans on other samples Mattia Ortino

13. ESR13 project state of the art • APC • No APC ESR13 ESR13 Next steps Mattia Ortino

14. ESR13 3 tapes • 4 samplesreiceved • Milestones: 1 wire • Magnetometry (SQUID)- • In the range of temperature from 5 to 39 K; Magnetic moment of wire sample as a function of temperature - M(T) curve for assessing Tc distribution. • Hysteresis loops (Jc) and Bc2 (SQUID) + MgB2powder • Scanning Hall Probe Microscopy (SHPM) – • In the range of temperature from 5 to 39 K; Magnetization maps of individual sub-elements, • Tc distribution within sub-elements (if possible) • Jc from Biot-Savart law inversion Together with ESR7 (M.Donato, ASG Superconductors) Mattia Ortino

15. ESR13 • AC Magnetometry • Sample preparation • Jcfrom Hysteresis Loops Mattia Ortino

16. ESR13 Only one tape analysed so far • SHPM : Remnant field-state measurements Remnant field profile of single sub-element 10K, 2T applied High magnetic background (Nichel) On thin slices (<80 μm) reliableJcextrapolationfromBiot-Savartinversion (resultscomparablewiththosefromresistivemeasurements) Mattia Ortino

17. ESR13 project state of the art • APC • No APC ESR13 ESR13 Next steps Mattia Ortino

18. Next steps APC • Sample preparation getting more important: new thin slices required for SHPM • Analyse local properties data (radial inhomogeneities, local currents) and relate them with microstructural ones • Analyse magnetometry data for Jc and Bc2 evaluation no APC • Focus on samples with innovative layouts (T7 & T8) for local properties investigation • Isolate sub-elements (Cu-etching) for individual magnetic measurements • Relate results with microstructural ones (barriers width, elemental composition) • New samples (new powder composition, new doping) coming: compare and understand performance differences from Jc and granulometry data • Etching of Nichel/Monel from bulk samples in order to measure with less magnetic background • Secondment in ASG Superconductors in October Mattia Ortino

19. Thanks for your attention! Mattia Ortino