1 / 23

Enhancement of J c and B irr on Binary and Alloyed in situ MgB 2 wires by

Enhancement of J c and B irr on Binary and Alloyed in situ MgB 2 wires by a new method: Cold High Pressure Densification. M.S.A. Hossain, C. Senatore, R. Flükiger DPMC & MANEP University of Geneva, 1211 Geneva, Switzerland. Outline Introduction

enye
Download Presentation

Enhancement of J c and B irr on Binary and Alloyed in situ MgB 2 wires by

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Enhancement of Jc and Birr on Binary and Alloyed in situ MgB2 wires by a new method: Cold High Pressure Densification M.S.A. Hossain, C. Senatore, R. Flükiger DPMC & MANEP University of Geneva, 1211 Geneva, Switzerland .ExCo Meeting Tampere, 18.5.2009

  2. Outline Introduction Cold High Pressure Densîfication on Binary MgB2 wires Effects on microstructure and mass density Effects on Jc and Birr Model for explaining the pressure effects Malic acid alloyed wires and tapes Carbon alloyed wires and tapes Conclusions .ExCo Meeting Tampere, 18.5.2009

  3. Definition: Field at which Jc = 1 x 104 A/cm2 : B(104) Mass density in in situ wires:~ 50% of 2.67 g/cm3 High temperature – High pressure treatments A Serquis et al., HIP on binary MgB2DB(104) = + 1T Appl. Phys. Lett., 82(2003)2847 T Prikhna et al., 2kbar, on Ti alloyed MgB2DB(104) ~ + 1T J. Physics: Conf. Series, 97(2008)012022 Conclusion: Higher mass density leads to higher Jc and higher B(104) values However, these methods are industrially not practicable Need for new methods to enhance MgB2 mass densityin view of industrial applications .ExCo Meeting Tampere, 18.5.2009

  4. How to enhance mass densities in MgB2? * Infiltration method, initiated by Giunchi et al., 2005 Recently modified to wire application: * K. Togano, J.M. Hur, A., Matsumoto, H. Kumakura, SuST 22(2008) Highest Jc values so far in MgB2 wires: at 4.2 K, B(104) = 15 T No mass density of the tubular filaments is given. Probably very high mass density * Cold high pressure Densification * R. Flükiger, M.S.A. Hossain, C. Senatore, 2009 arxiv.org/ftp/arxiv/papers/0901/0901.4546, submitted to SuST * M.S.A. Hossain, C. Senatore, R. Flükiger, M.A. Rindfleisch, M.J. Tomsic, J.H. Kim, S.X. Dou, submitted to SuST. .ExCo Meeting Tampere, 18.5.2009

  5. Binary MgB2 wires Fabrication of square wires, by applying pressure on 4 sides. .ExCo Meeting Tampere, 18.5.2009

  6. Binary Fe/MgB2 wire 1.0 mm 1.0 mm Drawn to a square cross section After cold densification at 3 GPa .ExCo Meeting Tampere, 18.5.2009

  7. Fe/ MgB2 filament at the border of a region pressed at 1.9 GPa (polished sample) .ExCo Meeting Tampere, 18.5.2009

  8. Reduction of voids in a Fe/MgB2 wire reacted at 650°C for 1 hour Without pressure Densified at 1.9 GPa. .ExCo Meeting Tampere, 18.5.2009

  9. Overall volume change in a Fe/MgB2 wire as a function of applied pressure Initially square wires: higher volume reduction than round ones after densification .ExCo Meeting Tampere, 18.5.2009

  10. Mass densities of filaments in Fe/MgB2 wires. Left scale: relative density dm of unreacted (Mg+B) mixture Right scale: relative mass density df of reacted MgB2 filaments .ExCo Meeting Tampere, 18.5.2009

  11. Effect of pressure on Jc// at 4.2 K for a Fe/MgB2 wire .ExCo Meeting Tampere, 18.5.2009

  12. Correlation between Jc and MgB2 mass density df df (%) .ExCo Meeting Tampere, 18.5.2009

  13. C4H6O5 Alloyed MgB2 tapes C4H6O5 Alloyed MgB2 wires .ExCo Meeting Tampere, 18.5.2009

  14. Variation of Jc// with pressure .ExCo Meeting Tampere, 18.5.2009

  15. .ExCo Meeting Tampere, 18.5.2009

  16. C4H6O5 Alloyed MgB2 wires NbTi Almost isotropic behavior, even at 4.2 K .ExCo Meeting Tampere, 18.5.2009

  17. C4H6O5 Alloyed MgB2 wires Isotropic behavior at 4.2 and 20K Highest Jc value reported so far for in situ wires .ExCo Meeting Tampere, 18.5.2009

  18. Pressure induces a densification and an increase of connectivity However, this does not explain * why the enhancement of Jc at 20K is so much higher * Why Birr is enhanced This effect can be understood by taking into account the Tc distribution in the MgB2 filament distribution model, based on specific heat measurements .ExCo Meeting Tampere, 18.5.2009

  19. .ExCo Meeting Tampere, 18.5.2009

  20. Distribution model Tc distribution in MgB2 bulk Samples by calorimetry Model: narrower distribution induced by high pressures Senatore C, Lezza P, Lortz R, Shcherbakova O Yeoh W K, Dou S X and Flükiger R IEEE Trans. Appl. Supercond. 17(2007)2941 .ExCo Meeting Tampere, 18.5.2009

  21. Distribution model Tc onset is the same, but low Tctailisshifted to higher values the superconducting surface increases The existence of a Tc distribution meansthatthereisalso a distribution of Birr and Bc2. Increase of Birr .ExCo Meeting Tampere, 18.5.2009

  22. Conclusions: Higher MgB2 mass density has been obtained by Cold High Pressure Densification (CHPD) Strong enhancement of Jc and Birr has been observed in binary MgB2 wires 4.2K/10T: DTc = 53%, 20K/5T: DTc = 300% C4H6O5 alloyed MgB2 wires: 4.2K/10T: DTc = 100%, 20K/5T: DTc = 400% Square MgB2 wires with practically isotropic properties exhibited the highest value of Jc reported so far: B(104) = 12.7 T at 4.2K. B(104) = 6.0 T at 20K Further improvements are expected after optimizing the densification process, shifting the crack-free limit to higher pressures CHPD has the potential for industrial production of long MgB2 wires .ExCo Meeting Tampere, 18.5.2009

More Related