Figure 1
The two wire geometries, round wires and thin films, investigated here for self-field J c showing coordinate system and dimensions. The film cross-section extends from x = −a to x = +a in width, and from y = −b to y = +b in thickness. Depicted are the two extremes when the wire radius, a, and film half-thickness, b, are either large compared with λ (left side) or small compared with λ (right side). The displayed formulae summarise our conclusions regarding (i) the global critical current density, J c , averaged over the full cross-section, (ii) the surface current density in the critical state, and (iii) the surface field in the critical state. Asymptotically, for both films or round wires, J c (sf) ∝ λ−3 in the small limit and J c (sf) ∝ λ−2 in the large limit.
