The bundle of magnets at the heart of the U.S. Department of Energy’s Princeton Plasma Physics Laboratory’s (PPPL) National Spherical Torus Experiment-Upgrade (NSTX-U) is the star of the show.
The bundle of magnets at the heart of the U.S. Department of Energy’s Princeton Plasma Physics Laboratory’s (PPPL) National Spherical Torus Experiment-Upgrade (NSTX-U) is the star of the show.
Its magnets will produce the highest magnetic field of any large spherical torus, allowing for near steady-state conditions. They are critical to the design of NSTX-U. When it begins operating, it will be essential in determining whether spherical tokamaks, which are smaller and more compact than traditional doughnut-shaped tokamaks, could provide a more efficient and cost-effective model for a fusion pilot plant.
The 19-foot toroidal field (TF) magnet carries up to 4 million amps of electric current to stabilize and confine the superhot plasma in fusion experiments. It will eventually connect to 12 TF coils on the outside of the vacuum vessel. Wrapped around it like a slinky is the ohmic heating (OH) coil, a 4-kilovolt magnet that induces an electric field, which drives an electric current into the vessel and helps to heat the plasma.
While the TF-OH magnet bundle is being assembled at Elytt Energy in Spain, the NSTX-U project team has found a clever, cost-effective way to prepare for its arrival by using an understudy for the star. It is made of red plastic and stands just 40 inches tall and 2 feet wide, but it is an exact replica of the top of the bundle.
« If it were a Hollywood set and you painted the TF-OH 3D print a different color, it would look just like the machine », said Tom Jernigan, a senior project manager on the NSTX-U project. « It’s the best money we ever spent. »
The 3D model is part of a larger strategy to pre-fit all the components of the experiment in advance before beginning operations in 2026, said Dave Micheletti, the NSTX-U project director and deputy associate laboratory director for engineering.
