Pinning Force Flux Lines

Fig. 5. Flux pinning in superconductors (a) strong pinning through the core interaction by normal conducting precipitates of various shapes (b) schematic view of the pinning potentials without (top panel) and under the action of a Lorentz force (bottom panel) (c) schematic view of pinning of a single flux line by the collective action of many small point pinning centres (after Ullmaier 1975).

In NbsSn superconductors the flux lines are pinned by the grain boundaries in the Nb3Sn filaments. The dependence of the effective volume pinning force Fp on the grain size is shown in Fig. 4.2-14. This leads to the requirement that the reaction temperature is optimized not... 

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