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Bi 2 Sr 2 CaCu 2 O 8+x (Bi-2212) is the only high-field, high-temperature superconductor (HTS) capable of reaching a critical current density J c (16 T, 4.2 K) of 6500 A • mm −2 in the highly desirable round wire (RW) form. However, state-of-theart Bi-2212 conductors still have a critical current density (J c) to depairing current density (J d) ratio around 20 to 30 times lower than that of state-of-the-art Nb − Ti or REBCO. Previously, we have shown that recent improvements in Bi-2212 RW J c are due to improved connectivity associated with optimization of the heat treatment process, and most recently due to a transition to a finer and more uniform powder manufactured by Engi-Mat. One quantitative measure of connectivity may be the critical current (I c) distribution, since the local I c in a wire can vary along the length due to variable vortex-microstructure interactions and to factors such as filament shape variations, grain-to-grain connectivity variations and blocking secondary phase distributions. Modeling the experimental V − I transition measured on a low resistance shunt as a complex sum of voltage contributions of individual filament and wire subsections allows a numerical extraction of the I c distribution from the d 2 V/dI 2 treatment of the V − I curves. Here we compare ∼ 0.1 m length I c distributions of Bi-2212 RWs with recent state-of-the-art very high-J c Engi-Mat powder and lower J c and older Nexans granulate powder. We do find that the I c spread for Bi-2212 wires is about twice the relative standard of high-J c Nb − Ti well below H irr. We do not yet see any obvious contribution of the Bi-2212 anisotropy to the I c distribution and are rather encouraged that these Bi-2212 round wires show relative I c distributions not too far from high-J c Nb − Ti wires.

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