Next Generation Superconducting Strands for Current Distribution Systems

Presently Hyper Tech is collaborating with CERN on MgB2 superconducting distribution cables. While the present generation of MgB2 wire is good enough for small scale cable demonstrations, there is a need to further improve the strand, specifically the minimum bend radius. There are basically two approaches to bringing about the improvement: either increasing the irreversible strain limit or reducing the size of conductor. The latter approach unfortunately reduces critical current of the wire and so was not favorably considered as a viable solution. The Key Innovation for this SBIR Proposal is the recent emergence of a new generation of MgB2 wires with breakthrough properties: this yet-to-be optimized wire fabricated by a modified and enhanced diffusion method has achieved a 10-fold increase in critical current density, Jc, over todays commercial MgB2 wires, and has the potential for a five-fold increase in engineering current density Je, or critical current, Ic, at a given diameter. This is a transformational advancement that would open up new opportunities for distribution cable applications in High Energy Physics. Incorporating this next-generation, high performance MgB2 strand into a cable to carry high current with stability requires improvement in several strand characteristics such as strain tolerance. The spectacular improvement in Jc and Je of 2nd generation MgB2 provide an excellent opportunity to overcoming the bend radius limitation by processing smaller wire sizes that produce the same Ic of 1st generation MgB2 wires. We are proposing new wire designs and wire processing technologies that would produce fine filamentary 2nd generation MgB2 strand while maintaining high Je, resulting in wire of larger bending strain limit leading to dramatic improvement in cable performance, and ultimately dramatic reductions in cost of MgB2 strands for cabling. Hyper Techs technical approaches are to: Investigate multifilament MgB2 samples of different wire configurations and material choices, with filament size as a parameter, and the best performing and most workable wire option will be selected for further development; Determine the bending strain limit on wires developed to determine their bending strain properties; Fabricate and characterize model cables using the wires developed. Commercial Applications and Other Benefits: The superconductor wire samples and prototype cables developed under this program are expected to impact the medical and energy industries from accelerated incorporation of these wires in a wide range of commercial applications such as MRI systems, fault current limiters, power utility transformers, motors, generators, and military applications. Additionally, improved MgB2 developed would compete with existing materials on both performance and cost for certain low field applications in high energy physics.