Scientists Fused Two Methods to Contain Nuclear Plasma
New research suggests two methods could work together to better contain nuclear plasma.
Nuclear fusion energy is a “holy grail” idea, but we have a long way to go to make it happen.
No one to date has demonstrated a reactor that’s even close to generating net energy.
In a new peer-reviewed paper, scientists have combined two leading models of fusion containment into a hybrid model that could work better than the sum of its parts. The paper appears in the International Atomic Energy Agency journal Nuclear Fusion, with coauthors from Princeton Plasma Physics Laboratory (PPPL), Columbia University, and the Max Planck Institute for Plasma Physics in Germany. Research like this embodies the race to contain nuclear plasma, which is the biggest sticking point to date in making a reactor that could make energy. That’s on top of a number of logistical and scientific obstacles that are still waiting to be solved.
Nuclear fusion is one of the holy grails of modern science. The nuclear reaction involves forcing particles together, which releases an enormous amount of energy. It’s the same physics eruption that powers many nuclear weapons. That’s compared to our current ecosystem of nuclear fission reactors, where particles are instead divided. Fission reactions happen at much lower temperatures and require much less shielding or elaborate containment, but they also produce much less energy than proponents say a nuclear fusion power plant could produce.
The problem is—and it’s a big one—successful nuclear fusion for energy is very, very far away. Today’s milestones are often reported without the fact that these facilities take an enormous amount of energy in order to get up to productive speed. Ignoring that high energy cost creates a misleading media climate, like reporting a company’s gross income as its profits. Fusion reactors also can’t run for more than a short time because of plasma containment.
It’s a scientific puzzle to contain a swirling mass that’s as hot as a star, and which could easily melt anything on Earth that it ever touched. These reactors, called tokamaks, include PPPL’s own DIII-D tokamak which is the subject of this research study. Physicists have spent decades working on magnetic fields to contain the plasma. Still, the edges are vulnerable to edge-localized modes (ELMs), while the interior of the donut-shaped plasma stream can experience hot spots from the magnetic field itself.
Two leading methods to safely contain plasma are electron cyclotron current drive (ECCD) and resonant magnetic perturbations (RMP). ECCD involves heating electrons in one direction to reduce collisions with electrons going the other direction. This reduces chaotic reactions within the stream in order to keep plasma better confined. RMPs are “spiraling rippled magnetic fields” that can be used on the surface to calm edge nodes, with hot spots, or magnetic islands, as a side effect.
Using both methods together, scientists believe they can use RMP to bring edge nodes into line and then ECCD to “heal” the resulting islands. ECCD, which is done using microwaves, was thought to be too potentially damaging to nuclear fusion reactor equipment. Lead author Qiming Hu of PPPL said in a press release that this isn’t the case. Hu specializes in ELM control and is part of another recent publication on modulating magnetic fields to reduce them in Korea’s KSTAR tokamak reactor.
“We’ve shown that it’s doable, and we’ve demonstrated the flexibility of the approach. This might open new avenues for designing future devices,” he said.
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