Nb3Ge as a Potential Candidate Material for 15- to 25-T Magnets
The Nb3Ge compound is a promising candidate material for superconducting magnets in the 15- to 25-T range at 4.2 K. Preliminary work  on thin films of sputtered material revealed that this A15 superconductor possessed an upper critical field (H c2) around 37 T at 4.2 K and a critical temperature, T c , of 22 to 23 K. Measurements of the critical current density, J c , gave a value of 1 GA m−2 at 21 T and 4.2 K, the highest recorded value at this field. J c values in the range 0.5 to 1 GA m−2 at the operating field density and temperature are considered adequate for constructing a magnet. Therefore, Nb3Ge is indeed a promising material for very high field applications. Growth of Nb3Ge by chemical vapor deposition (CVD) lends itself readily to the manufacture of lengths of conductor in tape form. This work concentrates on the CVD material. Other fabrication techniques, such as electron beam evaporation or high-rate magnetron sputtering, could also be amenable to the production of lengths of tape conductor.
KeywordsDepression Coherence Expense Sapphire Tantalum
upper critical field
perpendicular magnetic field
parallel magnetic field
critical current density
transition temperature width
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