Bi2Sr2CaCu2O8-x (Bi-2212) is a superconductor capable of producing large magnetic fields for advanced magnet systems. However, fluctuations in the size and shape of Bi-2212 filaments in a composite wire can affect processing capability. In this work, we compare the geometric filament uniformity of green-state densified composite Bi-2212/Ag wires to that of bronze route and powder-in-tube Nb3Sn wires in both the longitudinal and transverse orientations and explore the benefits and limitations of this technique. Filament size is the most important parameter to achieve overall uniform filaments, and transverse uniformity (which is much easier to measure) is an acceptable substitute for longitudinal uniformity in most situations. Finally, across a wide cross-section of Bi-2212 wires, the wire JE is shown to be only loosely correlated to the wire uniformity, as measured by the longitudinal coefficient of variation of the filament area. This points to the importance of powder quality and heat treatments as the primary drivers in Bi-2212 wire performance.
