A persistent asymmetry in fusion exhaust has challenged researchers for years. New simulations show that plasma core rotation, working together with cross-field drifts, determines where particles land inside a tokamak.
Tokamaks are often described as giant magnetic “doughnuts,” built to keep an ultra-hot soup of charged particles suspended long enough for atomic nuclei to fuse and release energy. But even in the best magnetic cages, some of that plasma leaks out. When it does, the particles race along magnetic field lines into a specially engineered exhaust region called the divertor, which functions a bit like a high-tech tailpipe for a fusion reactor.
Down in the divertor, those particles slam into metal plates, lose heat, and can rebound back as neutral atoms. (The returning atoms help fuel the fusion reaction.) In principle, designers would like this exhaust to be predictable and spread out. In reality, experiments across tokamaks have kept showing the same troublesome skew: far more particles end up striking the inner divertor target than the outer one.
Where the exhaust lands determines where the heat concentrates, how quickly materials wear out, and how aggressively future reactors will need to cool and protect their divertor surfaces. For years, the most common explanation pointed to cross-field drifts inside the divertor, meaning particles sliding sideways across magnetic field lines instead of neatly following them.
The idea made sense, but there was a major problem: computer simulations that included only these drifts still could not reproduce the strong inner target “preference” seen in real machines. If the models cannot get that basic pattern right, it becomes much harder to trust them for predicting how next generation devices will behave under even harsher conditions.
The Missing Ingredient: Plasma Rotation
A new set of simulations suggests the missing piece is not in the divertor alone, but in how the plasma moves around the entire ring of the tokamak. The research team used the SOLPS-ITER modeling code to test how particles travel under different assumptions, and reported the results in Physical Review Letters.
Their key result is that the models finally line up with experimental measurements when plasma core rotation is included alongside cross-field drifts. In other words, the spinning motion of the plasma in the main body of the tokamak can drive flows that reach all the way to the edge and reshape where the exhaust ends up.
“There are two components to flow in a plasma,” said Eric Emdee, an associate research physicist at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) and lead author of the study. “There’s cross-field flow, where particles drift sideways across the magnetic field lines, and parallel flow, where they travel along those lines. A lot of people said cross-field flow was what created the asymmetry. What this paper shows is that parallel flow, driven by the rotating core, matters just as much.”
Testing the Theory in DIII-D
To test the idea, the researchers simulated plasma conditions in the DIII-D tokamak in California. They examined four different cases, switching cross-field drifts and plasma rotation on and off to isolate their effects.
The models did not come close to matching experimental data until one crucial detail was added: the measured core rotation speed of 88.4 kilometers per second.
When both rotation and cross-field drifts were included, the predicted particle distribution aligned with observations. Together, these effects produced a much stronger influence than either one alone. The findings indicate that future fusion reactor designs must account for how the spinning plasma core shapes particle motion at the edge. Incorporating this connection into predictive models could help engineers build divertors that are better prepared for real operating conditions.
Reference: “Combined Influence of Rotation and Scrape-Off Layer Drifts on Recycling Asymmetries in Tokamak Plasmas” by E. D. Emdee, L. Horvath, A. Bortolon, R. Gerrú, G. J. Wilkie, S. R. Haskey and F. M. Laggner, 24 November 2025, Physical Review Letters.
DOI: 10.1103/zjpv-vxwd
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13 Comments
thanks for this
It is interesting how the energy demands of recently scaled up AI installations match the progress of successful fusion characteristics. It is not unlike the progress of neural computation techniques match with discoveries about how the human brain functions.
VERY GOOD!
The Topological Vortex Theory (TVT) provides a completely new geometric perspective for understanding the nature of spin. By reinterpreting spin as an emergent phenomenon of spacetime topological structure—specifically, the intrinsic topological charge of topological vortices—TVT successfully transforms fundamental problems such as spin quantization, spin-statistics correlation, and magnetic moment correspondence into topological invariant problems, achieving a unified and intuitive mathematical description.
—— Excerpted from https://zhuanlan.zhihu.com/p/2009216884604674814.
I have the answers to that and to TOE!
Tokamaks are often described as giant magnetic “doughnuts,” built to keep an ultra-hot soup of charged particles suspended long enough for atomic nuclei to fuse and release energy . In reality, experiments across tokamaks have kept showing the same troublesome skew: far more particles end up striking the inner divertor target than the outer one. My Question does the rotation speed of the plasma differ enough between the inner and outer donut shape cause the reason why more partials fall to the center of what might be called a gravity well in the center .
Are relativistic effects changing the apparent mass of the particles?
They are trying to solve the problems they face in confining the plasma, hoping that fusion will happen automatically if the plasma is confined for enough time. But, there is no solid proof for that.
Fusion is a forced-process. We have to confine the plasma and the cause fusion by applying more force. Fusion-reactors are theoretically not feasible.
Please ask the researchers to think deeply:
1. Does the plasma in space come from the topological phase transition of space itself, or from God, devil, or angel?
2. Is the God particle that physics is searching for everywhere today from God?
3. Are things in space derived from the topological evolution of space itself or from God?
Are these science?
Example 1
Two sets of cobalt-60 are manually rotated in opposite directions, and even without detection, people around the world know that they will not be symmetrical because these two objects are not mirror images of each other at all. However, a group of so-called physicists and so-called academic publications do not believe it. They conducted experiments and the results were indeed asymmetric, but they still firmly believed that these two objects were mirror images of each other, and the asymmetry was due to a violation of the previous natural laws (CP violation). In the history of science, there can never be a dirtier and uglier operation and explanation than this.
—— Excerpted from https://scitechdaily.com/what-happens-when-light-gains-extra-dimensions/#comment-947619.
Example 2
Please see how the so-called “mystery of θ – τ” is explained: θ and τ are completely identical in all measurable physical properties such as mass, lifetime, charge, spin, etc. However, experimental observations have shown that the θ meson decays into two π mesons, while the τ meson decays into three π mesons, making it difficult for physicists to explain why they are so similar. Physicist Martin Block proposed a highly challenging idea: θ and τ are the same particle, but in weak interactions, parity is not conserved. An easy to understand explanation is the following analogy:: There are two boxes of apples with identical weight, color, and taste. However, when one box is opened, there are two apples, while when the other box is opened, there are three apples. This confuses the old farmer who buys apples. He circled around the orchard and came up with a highly challenging idea: these two boxes of apples are not from the same tree, so they are the same.
—— Excerpted from https://scitechdaily.com/what-happens-when-light-gains-extra-dimensions/#comment-947686.
Everyone who has a reverence for natural laws and regulations deserves respect.
I asked AI , Is the sun divided into separate pools of circulating plasma that have a directional circulation from the center of the sun to a bulge at the top something like the circulation takes particles to the center and crushes them to use as fuel then ignites under the pressure . ( check it out ) Have always thought about this when trying to imitate how plasma is generated from the sun and cross reference that mechanics of the machine , the diverter collection and suns reprocessing to fuel again are similar processes that gather then presurers for fusion in the Granules formation all around the surface of the sun .
I asked AI. It said these are science:
Example 1
Two sets of cobalt-60 are manually rotated in opposite directions, and even without detection, people around the world know that they will not be symmetrical because these two objects are not mirror images of each other at all. However, a group of so-called physicists and so-called academic publications do not believe it. They conducted experiments and the results were indeed asymmetric, but they still firmly believed that these two objects were mirror images of each other, and the asymmetry was due to a violation of the previous natural laws (CP violation). In the history of science, there can never be a dirtier and uglier operation and explanation than this.
—— Excerpted from https://scitechdaily.com/what-happens-when-light-gains-extra-dimensions/#comment-947619.
Example 2
Please see how the so-called “mystery of θ – τ” is explained: θ and τ are completely identical in all measurable physical properties such as mass, lifetime, charge, spin, etc. However, experimental observations have shown that the θ meson decays into two π mesons, while the τ meson decays into three π mesons, making it difficult for physicists to explain why they are so similar. Physicist Martin Block proposed a highly challenging idea: θ and τ are the same particle, but in weak interactions, parity is not conserved. An easy to understand explanation is the following analogy:: There are two boxes of apples with identical weight, color, and taste. However, when one box is opened, there are two apples, while when the other box is opened, there are three apples. This confuses the old farmer who buys apples. He circled around the orchard and came up with a highly challenging idea: these two boxes of apples are not from the same tree, so they are the same.
—— Excerpted from https://scitechdaily.com/what-happens-when-light-gains-extra-dimensions/#comment-947686.
Everyone who has a reverence for natural laws and regulations deserves respect.
Please ask researchers to think deeply:
1. Is it scientific to use artificial mirror material to negate natural mirror material?
2. Is simulating the natural spinning of the sun through manual rotation comprehensive?
3. Which is more important, the electromagnetic properties of the sun or its temperature?
Based on the Topological Vortiex Theory (TVT), the principle of solar energy is to induce quantum effects locally through long-range electromagnetic effects.