This is a scientific first that enables mostly off the shelf magnet for simple and low cost experiments to test new concepts for future fusion power plants.

It does not generate net energy, but it has some nuclear processes and it is useful for experiments. 100 times cheaper but it is a device that is useful for experimental physics and nuclear fusion tests.

Stellarators typically rely on complicated electromagnets that have complex shapes and create their magnetic fields through the flow of electricity. Those electromagnets must be built precisely with very little room for error, increasing their cost. However, permanent magnets, like the magnets that hold art to refrigerator doors, do not need electric currents to create their fields. They can also be ordered off the shelf from industrial suppliers and then embedded in a 3D-printed shell around the device's vacuum vessel, which holds the plasma.

"MUSE is largely constructed with commercially available parts," said Michael Zarnstorff, a senior research physicist at PPPL. "By working with 3D-printing companies and magnet suppliers, we can shop around and buy the precision we need instead of making it ourselves."

They purchased more than 10 000 magnets at commercially available specifications: 5 % tolerance on magnetisation magnitude, 3? tolerance on magnetization orientation and 1 mm tolerance in physical dimensions. Multi-jet fusion 3D-print technology was selected for fabricating the PM holders using nylon plastic.

Using the magnetic surface charge method, the static assembled force between the 4 PM (permanent magnet) holders is calculated to be less than 1000 N. Most of the inter-magnet forces are carried as internal stress in the PM holders. Loading these forces into ANSYS, the peak internal stress was found to be less than 7 MPa, which is safely below the 30 MPa tensile strength of our 3D-print material. Finite permeability effects were also modelled. They found that the small but finite changes to stellarator metrics can be compensated for by slightly adjusting the TF coil current.