FILAMENTS4FUSION project delivers key achievement

The European technology development project, FILAMENTS4FUSION, funded through the Eurostars programme, has reached another key achievement – validating a method for cheap production of a proven technology, unlocking the potential of scalable low-cost production of filamentised superconductor tapes for fusion.

In principle, superconductors act as perfect conductors with zero resistance – and in most situations this is true – but under certain conditions, like under AC operation, some losses are generated, in part due to varying induced magnetic fields. These varying fields create screening currents – one of the primary sources of losses – which scale with the width of the tape and the current being put through it. By dividing the tape into a series of narrow parallel filaments, the current throughput can be maintained through all the filaments in aggregate, while the losses are limited by the lower width and current throughput of each individual filament, reducing the total loss. This is the benefit of filamentisation.

Winding the filamentised tapes around a round core further prevents the filaments from coupling through stabilising metallisation layers. This would otherwise potentially leave the filamentisation ineffective. Combining the filamented topology with the wound tape configuration, allows for low-cost production of a conductor with lower energy losses and higher current throughput at scalable lengths.

Putting this theory into practice, state of the art filamentised superconductor tape prototypes have responded as anticipated when exposed to a varying magnetic field, demonstrating filament integrity as the tape is wound around a tubular core. These key results match theoretical predictions (reducing total losses by upwards of 96%), and strengthen findings from previous smaller scale studies. This represents an important achievement for the F4F project, boosting confidence in the underlying technology.

These results will be presented further and in more detail at the MT-28 International Conference on Magnet Technology in Aix-en-Provence in September 2023. Bringing together the latest and greatest developments in magnet technology and applications from research and industry, this year’s conference focusses on future applications of magnets in the lead areas of Fusion, High Energy Physics, Power Engineering and Medical Diagnostics.

Through the Eurostars-funded FILAMENTS4FUSION project, SUBRA A/S, Theva Dünnschichttechnik GmbH, Etch A/S, and the Institute of Electrical Engineering at the Slovak Academy of Sciences are enabling the most advanced superconductors for fusion reactors.