The ability to burn plasma is a critical step toward nuclear fusion, and scientists are now one step closer.
Nuclear fusion has long appeared futuristic and unreachable,
whether it's for powering a flying DeLorean or helping us break free from our
reliance on fossil fuels. Now, thanks to a recent analysis from Lawrence
Livermore National Laboratory's National Ignition Facility (NIF), this future is
finally becoming clear.
According to a research published in the journal Nature,
nuclear physicists from NIF have demonstrated through four experiments that
burning plasma is possible – a critical step on the path to full nuclear
fusion.
Omar Hurricane is a co-author on this work and the chief
scientist for the Livermore National Lab's Inertial Confinement Fusion Program.
These tests, he claims, are a technological accomplishment that moves nuclear
physics one step closer to duplicating the type of sustained nuclear fusion
that occurs inside a star's core.
Hurricane says, "These articles report on the first experiments to surpass this burning plasma threshold." "The physical conditions required to generate a burning plasma are extraordinary, and achieving them necessitates extremely fine control... allowing the potential for dramatically increasing fusion performance."
HERE’S THE BACKGROUND
When you think about nuclear energy, pictures of conical
smoke stakes that remind you of Homer Simpson's dreary desk job come to mind.
"Fission" is the term for this type of nuclear energy. It occurs when
atomic nuclei – the nuclei at the center of atoms — are split apart, releasing
energy bursts that power steam and generate electricity. While nuclear fission
is a more environmentally friendly option to oil and coal, it has been criticized
in the past for mismanagement of aged facilities (think of the Chernobyl
accident) and the hazardous waste it produces.
Nuclear fusion, on the other hand, has a far more positive
public image. Nuclear fusion might provide clean, self-sustaining, and
waste-free energy by smashing light nuclei together to create one heavy one
(e.g., two hydrogen atoms creating one helium atom). An independent energy
source might be crucial in a future where clean energy sources struggle to
generate power on overcast or calm days.
The problem is that nuclear fusion is not only extremely
difficult to achieve, but even quantifying important milestones, such as
burning plasma, is challenging, according to Hurricane.
"In order for fusion plasma to produce more energy than it took to create it," Hurricane continues, "it must first be able to heat itself ('self-heating') by retaining part of the energy generated during fusion." "A 'burning plasma' is defined as the point at which the fusion plasma's self-heating just exceeds the external sources of heating used to create it."
"However, because a burning plasma has no evident data signature," he writes, "we employ data inferences to determine if our plasma's energy balance has transitioned into a burning state or not."
Because of this uncertainty, determining whether their tests
have truly created burning plasma can be challenging, but Hurricane claims that
the team is certain in their latest publication that they have.
WHY IT MATTERS
The achievement of burning plasma does not indicate that
fusion energy will be available in our homes any time soon, but it is a
significant step forward.
Alex Zylstra, an experimental physicist at Livermore
National Lab, is the paper's first author. This finding, he claims, will move
fusion research one step closer to its objective of producing clean,
self-sustaining energy.
"The dream of fusion," Zylstra says Inverse,
"is that it can deliver a carbon-free, safe, and consistent source of
energy." "Creating a burning plasma is a significant step toward
showing energy generation from fusion that might be used to generate
electricity."
WHAT THEY DID
Here's how the team
went about achieving nuclear fusion in a laboratory on Earth:
- In a hollow container known as a hohlraum, a spherical capsule of deuterium-tritium fuel (which can be made in part from seawater) is put.
- To generate x-rays, 192 lasers are focused at the hohlraum in a procedure known as "indirect drive inertial confinement" fusion.
- The fuel capsule and hohlraum are heated by these x-rays, causing the fuel capsule to compress hundreds of times its original volume in a fraction of a second.
The team details four tests that used this technology in
their new publication, and Hurricane claims that by measuring the energy
balance in the plasma, they were able to calculate an energy production of up
to 170 kilojoules. While this doesn't quite match the amount of energy used to
start the reaction, it's a huge improvement over earlier trials.
WHAT’S NEXT
Because science is never set in stone, the authors point out
that the authors' recent Nature results were already surpassed in August by
another experiment of the same type at NIF. While the team released a press
statement on these findings in 2021, Hurricane claims that the team is now
working on a manuscript about them.
Finally, the findings in this and the upcoming study show
that self-sustaining nuclear fusion is no longer a science fiction concept.
However, it's possible that your fusion-powered vehicle will still have to
wait.
"Right now, our concentration is on science - NIF is an experimental facility, not a power plant," Zylstra explains.
References:
- Zylstra, A.B., Hurricane, O.A., Callahan, D.A. et al. Burning plasma achieved in inertial fusion. Nature 601, 542–548 (2022). https://doi.org/10.1038/s41586-021-04281-w
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