Daniel Creedon, a professor at The University of Melbourne, has broken new ground by 3D printing a superconducting microwave cavity. This could be the precursor to 3D printed superconductors at a sensible price, which will move the goalposts for electricity, engineering and electronics.
Superconducting cavities are exceptionally useful for research purposes. They store microwaves and essentially prevent the waves from losing energy. The microwaves and electrons on the surface of the cavities interact and, to be considered a true superconductor, it is essential that the resistance of the material is consistent and close to zero.
The cavity is multipurpose
Resonating microwaves have a variety of purposes. They provide ultra-sensitive motion detectors that can help to measure the speed of light thanks to their highly stable frequency. They can also accelerate charged particles inside an accelerator.
Current particle accelerators include the iconic Large Hadron Collider in Switzerland, the circular track that is currently the world’s best facility.
The cavities are precision devices, which cost a great deal to make with traditional methods due to the accuracy involved. 3D printing has helped slash the production time and costs and now the University of Melbourne has produced a superconducting cavity that is every bit as good as a traditional one in terms of its electrical properties.
What impact do materials have?
Creedon printed two separate cavities, selectively melting aluminium to create the precise shape layer-by-layer. This is actually the cheapest method and the team could have opted for a more advanced solution that would have eliminated one potential pitfall. Layer-by-layer printing can result in a rough wall, which in theory should be unacceptable for a precision application like this.
The second cavity was produced with the same method, with one significant difference. The aluminium was combined with 12% Silicon, compared to 0.8% in in the standard A1-6061 industrial aluminium alloy. Creedon employed an alloy with a lower percentage of iron, copper and magnesium, too, compared to the standard industrial alloy.
Creedon expected the second compound to be more effective, but the team found that the composition actually had no significant impact on the superconductivity of the cavities. Both became active superconductors at 1.2 Kelvin and the electrical properties of the two compounds was largely similar. The roughness of the walls didn’t stop the cavity proving effective either.
Removing Silicon was a big deal
They did improve its performance by polishing the inner surface, heating the cavity to 770K and then cooling it.
Effectively, this removed all traces of Silicon from the inner wall and it had a major impact, improving the Q factor by a factor of two.
There is clearly some work to be done with different compounds and post production treatments, but the early results are exceptionally encouraging. Creedon has found a way to potentially mass produce Superconducting Microwave Cavities, which could make them a viable option for a wider range of applications.
Superconductors were discovered in 1911 and they are slowly finding a home in the electrical grid, mobile phones and the medical world. The simple cost rules them out of some applications, though, and means they are used sparingly in others.
If the superconductors are now easier to produce and refine, we’re at the start of a new dawn. Cost effective superconductors can produce cleaner electricity, more efficient motors and advanced electronics. It’s the key to a brighter, smarter, better future.
Make no mistake this is a big deal.
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