Promising new fusion research is revealing how plasma can spontaneously generate its magnetic field, in a fundamental breakthrough for one of the world’s most important emergent energy technologies.
Researchers reported their plasma simulations in a recent paper published in Physical Review Letters, finally describing the underlying process that could drive future fusion research. The team says their work may be especially applicable to direct-drive inertial fusion, in which fusion is created through multiple lasers simultaneously striking a fuel pellet.
Plasmas Explained
The mass of super-hot charged particles that make up our sun and other stars is a natural form of plasma, a phenomenon that the new research also helps to illuminate. Yet the team’s main interest is in how this research could drive nuclear fusion, which is projected to become a major energy source in the coming decades.
While laboratory fusion was first achieved close to a century ago, controlled fusion was not achieved until the late 1950s, and it was not until 2022 that Lawrence Livermore National Laboratory achieved fusion ignition, finally unlocking the technology’s potential to produce more energy than was put into the system. With both rising energy costs due to global instability and a global climate crisis driven by anthropogenic carbon emissions, a cheap, safe, and emission-free energy solution like nuclear fusion could be a major boon to humanity.
Direct-Drive Nuclear Fusion
Beginning with a small, spherical fuel capsule, researchers aim high-powered lasers at it in unison to heat and compress the fuel, driving a fusion reaction. One of the greatest hazards in the process is that unpredictable magnetic fields can affect how heat moves through the plasma, something that simulations have been unable to account for. Given that simulations are among the most important tools for designing safe and effective fusion systems, accounting for this variable is essential.
Real-world laboratory experiments have shown that lasers can heat solid objects into superhot plasma in seconds and even observed the powerful magnetic fields forming within it, yet the mechanism behind their formation has remained elusive.
The researchers developed an advanced computer simulation that tracked plasma behavior during laser interaction and observed the impact of varying laser intensities. Notably, when the intensity hit a specific threshold, the plasma rapidly magnetized, producing a field up to 40 tesla in only a billionth of a second. The sudden magnetism was so dramatic that it eclipsed the Earth’s magnetic field a thousand-fold.
“The key advance in our simulations is that we do not prescribe the plasma conditions in advance,” lead author Kirill Lezhnin, an associate research physicist at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL), told The Debrief. “Instead, the laser creates the expanding plasma self-consistently inside the kinetic simulation, using newly developed laser ray tracing and improved collision physics.”
Plasma Imbalance
A temperature imbalance in the plasma under these extreme conditions is the root of the powerful and sudden magnetic field generation observed. As is typical with matter, the plasma expands under the high heat of an intense laser, producing an imbalance as the material cools faster in the direction of expansion than in perpendicular directions. This temperature imbalance then triggers the Weibel instability, which generates the field.
“The uniqueness of our work is that we show that even if the laser drive is very uniform, just by virtue of expansion, plasma can still generate magnetic fields,” said Lezhnin. “These fields could change the behavior of the system.”
Due to their high strength, these magnetic fields influence the plasma’s behavior and temperature, making their understanding essential to plasma fusion predictions. In their paper, the team also presented a criterion for determining the threshold across various lasers and targets, enabling others to apply the findings to future work.
“The threshold turns out to be somewhat smaller than I would have expected,” Lezhnin concluded. “It falls right around the typical intensity for common inertial fusion experiments, which makes these magnetic field effects very relevant to that research.”
The paper, “Expansion-Driven Self-Magnetization of High-Energy-Density Plasmas,” appeared in Physical Review Letters on March 20, 2026.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.