The greatest hurdle remains improving the current density by manufacturing more efficient materials. Larbalestier said superconducting current has a tendency to percolate through materials, rather than sailing through unimpeded, resulting in huge losses of energy. The Applied Superconductivity Center is in a unique position to study the problem by using a novel technology called magneto-optical imaging. Developed and patented by ASC scientist Anatolii Polyanskii, the device allows researchers to literally create a visual image of current flow and barriers through microscopic filaments of superconducting material. Larbalestier said the research found that much of the energy loss comes from two sources.
Some current is blocked by grain boundaries made when the material is crystallized.
The tape is about 2 millimeters thick, and filled with 85 filaments only a few microns thick. Electric current passes through this honeycomb of tiny wires. ASC scientist Cai Xue-Yu tested individual filaments extracted from these tapes and revealed cracks that were once invisible to scientists. Larbalestier said that cracks are difficult to eliminate completely from manufacturing, but this research points directly to new fabrication techniques to reduce the problem. Efficient superconducting wires could replace copper wire and provide 10 times the energy density of copper.