heart of a star

What a fusion breakthrough means for the future of clean energy

Scientists are now one step closer to true, self-sustaining nuclear fusion.

clean room scientists in NIF facility
Lawrence Livermore National Laboratory

At the heart of every star is a self-sustaining explosion powered by smashing atomic nuclei together at incredible speeds.

Through this raucous tussle, our star (and others like it) creates a stable source of energy that spreads light across our solar system. To the untrained eye, this process may seem terrifying or at least dangerous, but to nuclear scientists, it’s a source of inspiration.

Scientists have been experimenting with the creation of nuclear energy for decades and have used nuclear fission — the process of breaking atoms apart — to power everything from devasting atomic bombs to clean nuclear energy.

However, this kind of nuclear energy is different from cosmic inspired nuclear fusion in one significant way: it’s not self-sustaining. Creating enough energy on Earth to power this kind of reaction has been just out of reach for decades.

But that could soon be changing. First reported in August 2021, nuclear scientists from the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory have come closer than ever before to prove that self-sustaining nuclear fusion — or fusion ignition — is really possible.

After decades of work, scientists are one significant step closer to achieving true fusion.

Lawrence Livermore National Laboratory

The team was able to create more than 1.3 megajoules of energy — or up to 70 percent of the input energy — which is an 8-fold improvement from earlier this year and a 25-fold improvement from NIF’s 2018 record.

This achievement will not only advance the field of experimental nuclear physics but will open new pathways for scientists to better understand the clean energy potential of nuclear power as well as the power of the U.S.’s existing nuclear weapon stockpile.

What is nuclear fusion?

Nuclear energy on Earth is more often than not powered by nuclear fission, which creates a domino-like energy production by splitting atoms apart into smaller and smaller pieces using neutrons. This reaction is typically done using uranium or plutonium atoms and creates energy by using heat from the reaction to transform water into steam to produce electricity.

Fission isn’t necessarily easy — and can easily go wrong, such as the famous Chernobyl meltdown — but scientists have a lot of experience creating this reaction. Fusion, on the other hand, is much trickier.

Instead of breaking atoms apart, fusion works by smushing them together at incredible speeds. As a result, this process can change light atoms — like two hydrogen atoms — into a heavier atom, like one helium atom. The reaction creates many times more energy than fission and all without leaving dangerous radioactive waste behind.

What is the purpose of nuclear fusion?

Thanks to its increased energy potential and limited waste, nuclear fusion is an attractive solution for clean, nuclear energy. The most tangible use of this nuclear-created electricity would be powering homes, offices, and EVs, but scientists are also dreaming about developing a fusion-powered spacecraft as well with infinite energy to sail through the stars.

Nuclear weapons scientists are also interested in how improved simulations based on this reaction can help them better evaluate the power and safety of the U.S.’s existing thermonuclear stockpile without detonating a single bomb.

What is inertial confinement fusion?

There are a number of different ways that scientists try to persuade atoms to slam together, including magnetic tubes like those used at France’s ITER (International Thermonuclear Experimental Reactor).

However, the NIF experiment uses inertial confinement fusion, which uses lasers to heat up and explode a tightly packed pellet of hydrogen atoms. Here’s how it works:

  • A weak laser beam pulse (equivalent to 1 billionth of a Joule) is created and split through different fiber optic cables
  • As this light travels 1,500 meters through the NIF facility, it is eventually amplified to 4 million Joules using mirrors and optical switches and split into 192 sources — this all happens in less than a second
  • The super-charged laser light is then sent into a gold containment chamber called a “hohlraum” that is only the size of a dime. Inside this chamber is the nuclear fuel capsule which contains deuterium atoms (hydrogen with one neutron) and tritium atoms (hydrogen with two neutrons)
  • The 192 lasers are bounced all around the chamber in what is called an “indirect drive” warm up the outside of the fuel capsule until its outer layer explodes
  • Following Newton’s third law (which says, “For every action, there is an equal and opposite reaction”), the outward explosion of the capsule forces the interior to implode

Using 192 high-powered lasers, nuclear scientists are attempting to create a star on Earth.

Lawrence Livermore National Laboratory / National Ignition Facility & Photon Science

This inward explosion creates an incredibly dense environment — like that of a star — that reaches 100 million degrees Celsius. Altogether, this process creates nuclear fusion.

However, the problem facing scientists is how to sustain that energy once it’s created. This condition, known as fusion ignition, requires the explosion to produce more power than the laser beams being used to spark it. Such ignition would create up to 400 million Joules of self-sustaining energy.

It’s this crucial condition that NIF scientists came closer than ever before to reaching this year with the demonstration of 70 percent matching energy creation.

What’s next — While NIF may have surged ahead of the pack with its latest achievement, it’s far from the only reactor racing toward the finish line to prove fusion’s worth. In addition to other large reactors like ITER, startups like Helion Energy are also jockeying for their place in this energy space. Just this month, Helion earned $500 million in funding toward its goal of demonstrating net electricity production using “pulsed magnetic fusion.”

After decades of work, things do appear to be — quite literally — heating up for fusion reactors. As these facilities continue to refine and test their methods, it may be only a matter of time until Earth-bound stars become our new reality.

Editors Note: This story was updated on November 18th to clarify that Helion earned $500 million total, not $375 million as previously stated which was the amount funded by Y Combinator president Sam Altman, toward demonstrating the use of pulsed magnetic fusion.

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