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Giant leap for nuclear fusion as lasers blast new route to ultimate energy source

Researchers in the US have overcome a key barrier to making nuclear fusion reactors a reality. In results published in Nature…

True fusion will be way more impressive than this. Lawrence Livermore National Laboratory

Researchers in the US have overcome a key barrier to making nuclear fusion reactors a reality. In results published in Nature, scientists have shown that they can now produce more energy from fusion reactions than they put into igniting nuclear fuel for an experiment. The use of fusion as a source of energy remains a long way off, but the latest development is an important step towards that goal.

Nuclear fusion is the process that powers the sun and billions of other stars in the universe. If mastered, it could provide an unlimited source of clean energy because the raw materials are plentiful and the operation produces no carbon emissions.

During the fusion process, smaller atoms fuse into larger ones releasing huge amounts of energy. To achieve this on Earth, scientists have to create conditions similar to those at the centre of the sun, which involves creating very high pressures and temperatures.

There are two ways to achieve this: one uses lasers and is called inertial confinement fusion (ICF), another deploys magnets and is called magnetic confinement fusion (MCF). Omar Hurricane and colleagues at the Lawrence Livermore National Laboratory opted for ICF with the help of 192 high-energy lasers at the National Ignition Facility in the US, which was designed specifically to boost fusion research.

A typical fusion reaction at the facility takes weeks of preparation. But the fusion reaction is completed in an instant (150 picoseconds, to be precise, which is less than a billionth of a second). In that moment, at the core of the reaction the pressure is 150 billion times atmospheric pressure. The density and temperature of the plasma created is nearly three times that at the centre of the sun.

The most critical part of the reaction, and one that had been a real concern for Hurricane’s team, is the shape of the fuel capsule. The capsule is made from a polymer and is about 2mm in diameter – about the size of a paper pinhead. On the inside it is coated with deuterium and tritium – isotopes of hydrogen – that are frozen to be in a solid state.

Hohlraum geometry with a capsule inside. Dr. Eddie Dewald/LLNL

This capsule is placed inside a gold cylinder, where the 192 lasers are fired. The lasers hit the gold container which emit X-rays, which heat the pellet and make it implode instantly, causing a fusion reaction. According to Debbie Callahan, a co-author of the study: “When the lasers are fired, the capsule is compressed 35 times. That is like compressing a basketball to the size of a pea.”

The compression produces immense pressure and temperature leading to a fusion reaction. Problems with the process were overcome last September, when, for the first time, Hurricane was able to produce more energy output from a fusion reaction than the fuel put into it. Since then he has been able to repeat the experiment.

Hurricane’s current output, although more than the hydrogen fuel put into the reaction, is still 100 times less than the total energy put into the system, most of which is in the form of lasers. Yet, this is a big achievement because reaching ignition just became easier.

Hurricane hasn’t yet reached the stated goal of the NIF that is to achieve “ignition”, where nuclear fusion generates as much energy as the lasers supply. At that point it would be possible to make a sustainable power plant based on the technology.

Scientists have been trying to tame fusion power for more than 50 years, but with little success. Although the National Ignition Facility, a US$3.5-billion operation, was built for classified government research, half of its laser time was devoted to fusion with an aim to accelerate research.

Zulfikar Najmudin, a plasma physicist at Imperial College London said: “These results will come as a huge relief to scientists at NIF, who were very sure they could have achieved this a few years ago.”

With laser-mediated ICF showing positive results, the obvious question is how does it compare with magnet-mediated fusion? According to Stephen Cowley, director of Culham Centre for Fusion Energy in Oxfordshire, “The different measures of success make it hard to compare NIF’s results with those of ‘magnetic confinement’ fusion devices.”

Culham works with magnetic confinement where, in 1997, the facility generated 16MW of power for 24MW put into the device. “We have waited 60 years to get close to controlled fusion. We are now close in both magnetic and inertial. The engineering milestone is when the whole plant produces more energy than it consumes,” Cowley said.

That may happen at the fusion reactor ITER, under construction in France, which is expected to be the first power plant that produces more energy than it consumes to sustain a fusion reaction.

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15 Comments sorted by

  1. John Newton

    Author Journalist

    'Nuclear fusion is the process that powers the sun' So why not go straght to the source?

    Perhaps because there's a lot of profit to be made in digging up uranium?

    And i'm sure the science is very fascinating.

    But the sun is here. Now. every day.

    1. Simon Mansfield

      logged in via Facebook

      In reply to John Newton


      >>The most critical part of the reaction, and one that had been a real concern for Hurricane’s team, is the shape of the fuel capsule. The capsule is made from a polymer and is about 2mm in diameter – about the size of a paper pinhead. On the inside it is coated with deuterium and tritium – isotopes of hydrogen – that are frozen to be in a solid state.<<

    2. Justin Ditton


      In reply to John Newton

      As Simon has pointed out, no Uranium is used in nuclear fusion reactors (as opposed to the nuclear fission reactors which already exist as a viable energy source). The fuel for a nuclear fusion reactor is hydrogen (in its various isotopes) which can be obtained in almost limitless quantities without any mining. Further there is zero risk of a nuclear meltdown.

      Solar power should continue to be a part of our ongoing energy production mix, but it is never wise to invest everything we have in one technology. If nuclear fusion has the potential to be a safe, cheap, clean and abundent energy source, what possible objection could there be to investigating it further?

    3. James Hill

      Industrial Designer

      In reply to Justin Ditton

      The fusion reaction in the sun turns hydrogen into helium with mass being turned into energy.
      It is not obvious to every reader that this is the fusion process, and the article makes no mention of the fusion products produced in the experiment.
      So if readers become confused, then perhaps the manner in which the article was written or edited might contribute to that confusion.
      Confusion about fusion?
      Completely avoidable, just reiterate the science, and don't assume that every reader is already adequately informed.

    4. Justin Ditton


      In reply to James Hill

      Thanks for the reply James, and I agree with your comments. While the article does set out the fuel which is used in the reaction, it could be clearer and the output is not really mentioned.

      I think it is a shame that every article on nuclear fusion should need to be prefaced by addressing negative perceptions associated with nuclear fission which have no application to fusion technology. But perhaps it is just something science journalists will have to put up with, at least until the technology is more mature and better understood.

    5. John Newton

      Author Journalist

      In reply to Justin Ditton

      Thank you for correcting me Justin. I seen nuclear, and think uranium. I will read further.

  2. Fred Pribac

    logged in via email

    In 1981 I wrote an essay as part of my physics degree - "Fusion - destiny or delusion".

    The then thinking was that the fusion boys were just two or three decades from breakeven and that the magnetic boys were closer than the laser jocks.

    I loved the notion of hanessing fusion power and I came down on the side of destiny.

    Three decades later the magnetic boys are still closer than the laser jocks but the engineering task for both has proved so difficult that we are still "two or three…

    Read more
    1. Felix MacNeill

      Environmental Manager

      In reply to Fred Pribac

      Yeah, while this article is good news, we're still really nowhere near a practical application on an industrial scale - barring a few pretty remarkable breakthroughs which, though not inconievable, are not very likely.

      In practical terms, I think it reinforces the fact that the transformation of our current energy generation systems, which needs to happen over the next few decades if we're not to be 'roasted, toasted, fried and grilled.' will have to be effected with technology to hand.

      Still, if we do manage to pull it off, there's an outside chance we'll never need to build a second - or maybe third - generation of wind turbines and solar thermal installations, as we will have access to almost infinite and remarkably clean fusion power.

  3. Jack Ruffin
    Jack Ruffin is a Friend of The Conversation.

    logged in via email

    Great article in that it marks an important step on the way to the goal of energy with little pollution. As the science develops we need to provide more information to enable us all to understand the profound difference between fission and fusion. Given time for development, the fusion form of energy could contribute significantly to a safe mix of power sources that do not exacerbate detrimental climate change. Meanwhile we need to continue to push the development of solar and other " renewable" energy sources. The climate situation is too dire to defer action. I look forward to hearing of future developments.

  4. Colin Samundsett

    retired BSurv

    let there be no confusion - if we harness fusion; and this time the dream of being "too cheap to meter" turns into reality - what then? We will be harnessed to a horse that has bolted: unlimited energy to exploit the planet's limited resources. If we continue to have disconnect between social direction and the world of nature, as has been the case over the past seven human generations, the natural environment upon which we depend will be unable to sustain our species. Seven billion, rising towards 10 billion, people on this planet cannot aspire to "western" lifestyles - if, in fact, any lifestyle at all. We need more than fusion.

  5. Jack Jackersen


    Such an appropriate name for a fusion scientist;
    Omar Hurricane,

    At first i was like way cool,
    Energy out > energy in;

    But then half way down your jaw drops and its like,
    'This is just another funding troll'

    Once theoretically possible the idea would be to ban all patents to do with the technology;
    Thus the earth would become one level playing field.

    I think i'd like to smelt aluminum in my garage.

  6. Ken Fabian


    If it's so incredibly hard to do I think it is going to continue to go on being very hard to do. And consequently it will be expensive. How long to repay the R&D costs?

    There are technologies with enormous potential, with technological hurdles far less problematic that see less than a thousandth of the R&D funding that fusion gets. Some are going to be well suited to low cost mass production and simple deployment in remote villages by local handymen as easily as the world's centres of technological…

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    1. Justin Ditton


      In reply to Ken Fabian

      Ken, while I am sure you will be able to point to some proponents of fusion technology who have sold it as an immediate solution, I would suggest that those people are the exception rather than the rule. Most advocates for fusion technology do not make any claim that this technology will be viable in the short-term.

      But I object to the implication that, because it is decades away, or will take a long time to repay the R&D costs, it is somehow less worthy than projects with smaller, but more immediate returns. It is short-term thinking which got us into the current climate mess. Only long-term thinking can get us out of it.

      As I have said in a previous comment, pursuing fusion technology should not come at the expense of implementing solar, wind and other renewables now. But make no mistake, fusion technology is the long-term answer.