Low Cost Fabrication of 2G Wires for AC Applications

Second Generation (2G) High Temperature Superconducting (HTS) wires based on the YBCO coated conductor are expected to find use in many commercial and military applications not accessible to the First Generation (1G) BSCCO HTS wires. However, the use of these 2G wires in certain applications, such as synchronous generators with both superconducting rotor field windings and armature windings, requires that the conductor be engineered to minimize ac losses. The general approach to designing a low ac loss wire is to fabricate the YBCO films into narrow filaments and then to twist the resulting multi-filamentary conductors. However, a major challenge to achieving this design is developing an industrial method to fabricate the YBCO films into narrow filaments. We propose in this Phase I STTR program to evaluate a low-cost deposition process for directly depositing multi-filamentary YBCO conductors in a striated/striped architecture without a post deposition patterning step. Our proposed approach is based on a conventional graphic arts printing technique that is currently being adapted to low-cost/high throughput fabrication of complex, high value functional materials, such as ceramic films, diode displays, transistor circuits, and biochip arrays. The proposed program will focus on demonstrating the direct deposition of patterned arrays of YBCO stripes, determining the resolution of the technique, and evaluating the electrical properties of the patterned YBCO filaments. The anticipated Phase II program will focus on fabrication of continuous lengths of patterned, striated YBCO conductors that will be fabricated into low-loss ac conductors for testing in selected pertinent applications, such as a small synchronous generator.