Faulty reasoning signals

• Confirmation Bias - 13.2% (60 hits)
• Anchoring Bias - 5.1% (23 hits)
• Availability Heuristic - 2.4% (11 hits)
• Representativeness Heuristic - 0%
• Hindsight Bias - 0%
• Overconfidence Bias - 11% (50 hits)
• Framing Effect - 14.5% (66 hits)
• Loss Aversion - 0%
• Status Quo Bias - 0%
• Sunk Cost Effect - 8.8% (40 hits)
• Optimism Bias - 22.5% (102 hits)
• Pessimism Bias - 6.6% (30 hits)

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A potential hindrance to fusion power may help instead

A potential hindrance to fusion power may help instead

By tamping down turbulence, fusion's alpha particles could boost reactor performance

Fusion is the process that powers thes sun: Two atomic nuclei merge into one, releasing energy.

If it could be harnessed on Earth, fusion could generate energy without the carbon emissions of fossil fuels or the long-lived radioactive waste produced by nuclear reactors based on fission, the splitting of atomic nuclei.

Several companies are working to build commercially viable fusion reactors.

Interest in the technology is surging: On June 9, the U.S.

Department of Energy released a roadmap for fusion power in the coming decade.

But no reactor has yet generated the conditions under which fusion can flourish, and uncertainties swirl around the physics.

Alpha particles are key players in fusion reactors.

They carry energy that gets dumped into the surrounding plasma, heating it.

Once a reactor really gets going, it should become self-sustaining: The alpha particles produced by the fusion reactions heat the plasma, keeping conditions ripe for more fusion.

“If you don’t know how the alphas will behave, there is no way to make an economically viable reactor,” says plasma physicist Jacobo Varela of the University of Texas at Austin, who was not involved with the research.

“In a reactor, everything is about the alphas and how they behave.”

For the new study, plasma physicist Alessandro Di Siena and colleagues simulated two reactors currently under construction: ITER, an international research project in southern France, and SPARC in Devens, Mass., designed by Commonwealth Fusion Systems, which partly funded the study.

Both are doughnut-shaped devices called tokamaks that confine plasma with strong magnetic fields.

In the simulations, alpha particles kicked off flows of plasma that broke up small-scale turbulence, keeping the plasma hotter and better confined.

That produced more fusion and yet more alpha particles.

“What we see is that you can enter in a type of positive feedback loop,” says Di Siena, of the Max Planck Institute for Plasma Physics in Garching, Germany.

When this effect was included, alpha particle heating increased by up to 25 percent in SPARC and up to 18 percent in ITER.

There are still uncertainties in these types of simulations, including on the predicted heating boost of up to 25 percent.

So, as far as specific numbers go, “I would take it with something of a grain of salt,” says Phil Snyder, vice president of plasma physics at Commonwealth Fusion Systems.

But the overall trend is what’s important, he says.

When the alphas’ effect on turbulence is included, “you can end up producing significantly more fusion power than you would have predicted if you did not include this effect.”