U.S. tests spinning fuel with 180 million degrees Fahrenheit plasma for nuclear reactors

Scientists in the United States have been testing spin-polarized nuclear fuel in tokamaks operating at about 100 million degrees Celsius to explore a more efficient path to nuclear fusion through particle alignment.

The project, led by a research team at the U.S. Department of Energy’s (DOE) Thomas Jefferson National Accelerator Facility, aims to assess whether spin polarization, a method widely used in nuclear physics, can withstand extreme conditions inside magnetically confined fusion devices.

Scientists involved in the effort say the research is part of a broader effort to develop new and innovative approaches to harnessing star power for the world’s power grids.

Dr. Xiangdong Wei, a physicist at the Jefferson Institute and co-principal of the study, said the goal is to harvest energy with as little material as possible. “If tuned correctly, a smaller amount of fuel can create a larger fire, and that energy can be used for further fusion,” he revealed.

Reinventing fusion fuel

The experiment will be carried out in a DIII-D (D3D) tokamak, a device that uses magnetic fields to confine plasma within a doughnut-shaped chamber. As a result, the atomic nuclei collide and fuse, releasing a huge amount of energy.

The D3D tokamak is the largest in North America and is the primary platform for testing technology for future nuclear reactors such as ITER.

The spin-polarized fusion (SPF) project is a targeted investment that advances DOE’s fusion roadmap, according to Dr. Matthew Lanctot, acting director of the Fusion Energy Science Research Division in the DOE Office of Science.

“This activity aims to leverage the expertise in spin-polarized materials developed by the Nuclear Physics Program to influence relevant aspects of the fusion reaction itself,” Lanctott added. “If successful, it could theoretically have a significant impact on the fusion pilot plant.”

The new approach involves tuning a particle’s intrinsic spin, a quantum property that acts like a tiny magnet. If particles are oriented in the same direction, they are considered spin-polarized.

According to theory, this could significantly increase the probability of a fusion reaction by about 50 percent, in addition to increasing overall energy output by up to 80 percent while using less fuel.

Smarter fusion path

To test this concept, the team uses two isotopes with favorable properties: deuterium and helium-3. Most current fusion experiments rely on deuterium-tritium (DT) fuel, but tritium is rare and radioactive. In contrast, helium-3 has similar spin dynamics and doesn’t have the same supply or safety issues.

“However, you can make tritium using a reaction between neutrons and lithium,” emphasized Philip Dobrentz, a staff engineer at the Jefferson Institute working on the SPF project. “So, as it stands now, fusion has virtually no fuel supply limitations.”

Helium-3 is polarized using a technique inspired by medical MRI systems. Once the preparation is complete, the fuel must be carefully transported and injected into the tokamak without losing its position.

This process takes a few milliseconds and requires extremely low temperatures and precise control of magnetic fields. In Phase I, the team acquired lithium deuteride (LiD) to be used at Oak Ridge for pellet formation. LiDs are solid at room temperature, making them easy to store and transport, but difficult to polarize.

Meanwhile, the next stage will focus on building and integrating the entire system, including the pellet injector and diagnostic tools to measure whether polarized light persists in plasmas at 100 million Kelvin. The final test is scheduled for 2030, when fusion byproducts will be analyzed to confirm effectiveness.

If successful, spin-polarized fuel could enable smaller, cheaper fusion reactors with less stringent ignition requirements, accelerating the path to commercial fusion power. “The success of the project will sprout a research field within the fusion industry,” Dobrenz concluded in a press release.