A New Generation of In Situ MgB2 Wires With Improved J(c) and B-irr Values Obtained by Cold Densification (CHPD)

作者：Fluekiger Rene; Al Hossain Md Shahriar; Senatore Carmine; Buta Florin; Rindfleisch Matt

来源：IEEE Transactions on Applied Superconductivity, 2011, 21(3): 2649-2654.

DOI：10.1109/TASC.2010.2101571

• Cold densification
• critical current density
• electrical resistivity
• MgB2
• upper critical field

By means of Cold High Pressure Densification (CHPD), the critical current density, J(c), of binary and alloyed MgB2 wires has been enhanced by more than a factor 2 at 4.2 K and at fields up to 19 T. The relative MgB2 mass density of binary MgB2 wires was enhanced to similar to 54% after applying 2.5 GPa at 300 K before reaction. In C4H6O5 (malic acid) alloyed wires, densification also caused the enhancement of B-irr, as a consequence of a slightly enhanced C content, determined by X ray diffraction. Almost isotropic J(c) values were obtained for C4H6O5 added wires of 1 x 0.6 mm(2) cross section, the values of J(c) (4.2 K) = 1 x 10(4) A/cm(2) for parallel and perpendicular fields being obtained at 13.8 and 13.4 T, respectively (1 mu V/cm criterion). The corresponding values for 20 K were both close to 6.2 T. The value of B-irr(/) (/) at 20 K was 11 T.
The positive effects of cold densification on J(c) and B-irr on MgB2 was also observed on 150 mm long wires alloyed with C4H6O5 (malic acid) or with SiC, by the succession of 6 overlapping pressure steps.
This process can be extended to long wire lengths: by means of a newly developed prototype machine with an automatic press/release/advance sequence, a first wire length of 1 m was densified at 1.

• 出版日期2011-6