NIF Hohlraum (Artist’s rendering)

Nuclear fusion power breakthrough – Expert Reaction

US scientists have reportedly reached a milestone in nuclear fusion research, producing a net gain of energy for the first time.

Scientists at Lawrence Livermore National Laboratory in California have announced the success of an experiment at their National Ignition Facility. However analysis of the results are still underway, and far more work would be needed to make it a workable energy source.

The SMC asked experts to comment.

Dr Jonathan Squire, Research Fellow, University of Otago, comments:

“Fusion is the process that turns hydrogen into helium, releasing amazing amounts of energy in the process. At its core, this is actually where all energy on Earth comes from, since fusion is what powers the Sun. Because the fuel you need is basically limitless (it’s found in seawater) and the process doesn’t create any carbon emissions or nasty waste, if we get this working it will be an amazing boon for humanity.

“But, it’s incredibly difficult to make it work. Basically, you have to hold the gas (which becomes ionised plasma) and heat it up to insane temperatures and pressures – around 100 million degrees. There are two main approaches, called magnetic confinement and inertial confinement. Magnetic confinement tries to build a bottle (out of magnetic fields) to hold the plasma, then heats it up via various methods; inertial confinement instead compresses the gas suddenly using extremely high-powered lasers, creating a sudden burst of fusion that then stops. Today’s announcement is about the inertial method: they figured out how to create a pulse so strong that it caused more energy to come out of the fusion reaction than was needed initially to compress the gas.

“Fusion power has been long-term goal of humanity for 70 years now, and this is the first time we’ve created a process that’s given out more energy than we’ve put in. So, it’s hugely significant. It shows that it’s possible and feasible with current technology and methods. But, there’s still a lot of difficulty involved with making a commercial power plant, because you have to do what they did many times per second.

“I think we should see fusion as completely different from standard nuclear power, which is based on a totally different process (fission). Unlike standard nuclear, there is no way that a fusion plant can melt down – it’s so incredibly hard to make it work in the first place, that anything slightly wrong will just cause it to stop. And it doesn’t generate any radioactive waste from the reaction at all, just normal helium like we use to fill balloons.

“Whether New Zealand will ever need it for our power is a different question – maybe we have enough hydro, solar, wind and geothermal anyway. But we must remember that the process is completely different to standard nuclear power, as different as solar and wind power.”

No conflict of interest declared.

Professor Allan Blackman, School of Science, Auckland University of Technology, comments:

“We need to be careful when evaluating the news of the supposed significant breakthrough in controlled nuclear fusion. Those of you with long memories might recall the initial report of ‘cold’ fusion in 1989. This was announced by press conference, not the usual way to detail major scientific advances, and the parallels with the current announcement are obvious (last time I looked, the Financial Times wasn’t a scientific journal of repute). Let’s just all calm down a little and lower expectations at least until this work appears in a peer-reviewed scientific journal and has been replicated. If it passes these tests (and I hope it does) then yes, it will be a truly awesome achievement.”

No conflict of interest declared.

Dr David Krofcheck, Senior Lecturer in Physics, University of Auckland, comments:

“There are two types of nuclear energy production: fission, which is what most people think of when we say nuclear power; and fusion in which lighter nuclei are brought into close proximity so that they join together to form a heavier nucleus plus energy. In the Lawrence Livermore National Lab case at the National Ignition Facility two heavy types of hydrogen called deuterium (D) and tritium (T) are forced together to create lithium and a neutron. The neutron is important because it carries away a lot of kinetic energy that, in the future, could be used to produce heat in a surrounding water bath or in a molten salt mixture. This result is a huge scientific achievement as it appears to be the first time in which human beings generated more energy “out of the reaction” than was required to create or “go into the reaction; this is the first time that D-T fusion “ignition” was achieved.

“We should all take a deep breath because this was done in a single blast of highly symmetric light from 192 lasers focused on a 2 mm D-T sphere inside a gold cylinder. A practical nuclear fusion plant would require this feat to be achieved many times per second, generating a huge and continuous flux of neutrons that would be converted into heat and electricity.

No conflict of interest declared.

Our colleagues at the UK SMC have also gathered expert comments.

Prof Justin Wark, Professor of Physics at the University of Oxford and Director of the Oxford Centre for High Energy Density Science, comments:

“This result is a major breakthrough in fusion science.  The Lawrence Livermore National Laboratory uses the largest laser in the world to compress heavy hydrogen to conditions similar to those in the centre of the sun. The lasers enter the ends of a centimetre-scale cylinder, hitting its inner walls, making them glow x-ray hot,  These x-rays then heat a sphere at the centre that contains the nuclear fuel.  The outside of the sphere vaporises and becomes a plasma, that rushes off the surface, creating an imploding ’spherical rocket’ which in a few billionths of a second reaches velocities of order 400 kilometres per second.  The subsequent ‘crunch’ at the centre is tailored in a specific way to make a hot spark in the middle, and the density of the compressed ‘fuel’ surrounding the spark  is so great that the nuclear fusion reaction takes place in about a tenth of a billionth of a second – faster than the tiny hot sphere can fly apart.  It is thus confined by its own inertia, and thus this method of fusion is called inertial confinement fusion.  The other major approach – magnetic fusion – uses the same heavy hydrogen fuel, but with a plasma far less dense than normal air, and thus the nuclei bump into each other less frequently, and in that approach the plasma needs to kept in its magnetic ‘bottle’ for several seconds in order for enough reactions to take place.  The aim of both methods is to get more energy out than is put in.

“The Lawrence Livermore National Laboratory experiment shows that scientists can get more energy out than put in by the laser itself.  This is great progress indeed, but still more is needed: first we need to get much more out that is put in so to account for losses in generating the laser light etc (although the technology for creating efficient lasers has also leapt forward in recent years).  Secondly, the Lawrence Livermore National Laboratory could in principle produce this sort of result about once a day – a fusion power plant would need to do it ten times per second.  However, the important takeaway point is that the basic science is now clearly well understood, and this should spur further investment.  It is encouraging to see that the private sector is starting to wake up to the possibilities, although still long term, of these important emerging technologies.”

Conflict of interest statement: “Prof Wark is the UK academic member of the National Ignition Facility Peer Review Panel that gives advice on the fusion program at Lawrence Livermore National Laboratory.”

Dr Robbie Scott, of the Science and Technology Facilities Council’s (STFC) Central Laser Facility (CLF) Plasma Physics Group, who contributed to this research, comments:    

“Fusion “ignition” occurs when the power emitted by the fusion reactions exceeds the losses. Experiments on the National Ignition Facility are a bit like striking a match, with this experiment the match kept burning. This is a momentous achievement after 50 years of research into Laser Fusion.

“Fusion has the potential to provide a near-limitless, safe, clean, source of carbon-free baseload energy. This seminal result from the National Ignition Facility is the first laboratory demonstration of fusion ‘energy-gain’ – where more fusion energy is output than input by the laser beams. It cannot be understated what a huge breakthrough this is for laser fusion research. More importantly however, is that fact that it paves the way for the rapid development of Laser Inertial Fusion Energy – power generation by Laser Fusion.

“The experiment demonstrates unambiguously that the physics of Laser Fusion works. In order to transform NIF’s result into power production a lot of work remains, but this is a key step along the path. Next steps include the demonstration of even higher fusion energy-gain and the further development of more efficient methods to drive the implosion.

“This fantastic result was made possible by the work of hundreds of scientists and engineers over decades. My own contribution was to discover that if NIF’s implosions were not spherical, this would reduce the efficiency of the implosion and so the number of fusion reactions. Importantly, I also showed that certain non-spherical implosion shapes would appear to be perfectly spherical using NIF’s X-ray imaging diagnostics. This led to the development of new diagnostics for NIF which confirmed the implosions were non-spherical, just as predicted. This resulted in a multiyear effort at NIF to make the implosions as spherical as possible, improving NIF’s fusion yield.”

No conflict of interest declared.

Tony Roulstone, lecturer in nuclear energy at the University of Cambridge, comments:

“It is reported that the National Ignition Facility (NIF) has surpassed one of its own targets to exceed scientific energy gain.  They put 1.8 MJ and got 2.5 MJ out – proving that energy can been successfully released and gained by a Deuterium-Tritium fusion reaction. This is positive – the failure to achieve scientific energy gain in 2012 ended the run of experiments for which NIF was built. Now they have worked on the design and the make-up of the target and the shape of the energy pulse to get much better results.

“Although positive news, this result is still a long way from the actual energy gain required for the production of electricity.  That’s because they had to use 500 MJ of energy into the lasers to deliver 1.8 MJ to the target – so even though they got 2.5 MJ out, it’s still far less than the energy they needed for the lasers in the first place.  In other words, the energy output (largely heat energy) was still only 0.5% of the input.  An engineering target for fusion would be to recover much of the energy used in the process and get an energy gain of double the energy that went into the lasers – it needs to be double because the heat must be converted to electricity and you lose energy that way.

“Therefore we can say that this result from NIF is a success of the science – but still a long way from providing useful, abundant, clean energy.”

No conflict of interest declared.

Prof Gianluca Gregori, Professor of Physics at the University of Oxford who specialises in high power lasers and fusion energy, comments:

“For many years fusion energy has been described as the holy grail of the world’s energy problems – a limitless and clean energy source that would address the ever-increasing demands free from carbon emissions. The scientists at the Lawrence Livermore National Laboratory have achieved the long-sought milestone of proving for the first time breakeven thermonuclear fusion in the laboratory. The amount of energy released in the fusion reactions exceeded that of the input laser energy, demonstrating a positive energy gain. The fusion approach used at Lawrence Livermore requires the thousand-fold compression of matter to ultra-high densities and temperatures to mimic the compressional effect of gravity in the sun, nature’s very effective nuclear fusion reactor. While this is not yet an economically viable power plant (the costs of targets are still exorbitant, and the amount of energy released is yet smaller than wall plug electricity costs), the path for the future is much clearer.

“Today’s success rests upon the work done by many scientists in the US, UK and around the world. With ignition now achieved, not only fusion energy is unlocked, but also a door is opening to new science. Applications of inertial fusion-related research include the ability to study processes related to astrophysical turbulence and magnetic field generation in galaxy clusters, and to unravel the dynamics of matter compressed under extreme pressures as found in the cores of giant planets.”

No conflict of interest declared.

Our colleagues at the SMC Spain have gathered the following expert comments.

José Manuel Perlado Martín, Emeritus Professor of Nuclear Physics and President of the Instituto de Física Nuclear Guillermo Velarde (IFN-GV) at the Universidad Politécnica Madrid (UPM), comments:

“The current news was received on 7 December 2022 from our collaborators at Lawrence Livermore National Laboratory (LLNL) and other European and American laboratories associated with the “Guillermo Velarde” Nuclear Fusion Institute and will be confirmed tomorrow 13 December, according to the announcement of the press conference to be held in Washington by the US Secretary of Energy Jennifer M. Grandholm and the Under Secretary for Nuclear Security and National Nuclear Security Administration Jill Hruby.

“According to this information, on 5 December 2022, the National Ignition Facility (NIF) at LLNL in California (USA) achieved a net energy of 2.5 megajoules with a laser of 2.1 megajoules and, according to some sources, the possible achievement of up to 3 megajoules is under discussion.

“This means that for the first time in the history of physics and energy a nuclear fusion device, through the method of inertial confinement using a laser, has achieved ignition and energy gain in the laboratory.

“Experiments in January 2022 (published in Nature/Nature Physics on 26 January) had already achieved 1.3 megajoules with a laser shot of 1.7 megajoules, but also demonstrated the mechanism of propagation of the thermal wave of burning in the fuel, which gives confidence that more and more energy can be obtained in the process. This was repeated in September 2022 with an energy of 1.2 megajoules. It is now clearly demonstrated that the process is known and the key limit of obtaining more energy than is used in laser illumination of the deuterium and tritium fuel target is exceeded.

“This is a huge step towards believing that this can indeed be the massive and concentrated high energy density source that humanity needs.

“Clearly, there is still some way to go to realise this energy extracted from the bonding of hydrogen nuclei. But this achievement should mean that research into target illumination systems, fuel capsule manufacture, reaction chamber systems and materials suitable for the conditions of this fusion line must be substantially increased, unlike what has been happening in the European Union.

“For the “Guillermo Velarde” Nuclear Fusion Institute of the Polytechnic University of Madrid, officially created in 1982 for this research and unique in Spain, a consequence of the work begun by Professor Guillermo Velarde in the early 1970’s at the Nuclear Energy Board, it means the culmination of 40 years of belief and faith in the beauty and practical potential of this idea, on which thousands of articles have been published in its entirety both in the physics of the process and in the physics of the technology that would make the reality of a power plant feasible.”

No conflict of interest.

Carlos Hidalgo, Head of the Experimental Division of the National Fusion Laboratory, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), comments:

“The practical realisation of nuclear fusion energy is one of the great challenges facing humanity in the 21st century.

“The experimental results obtained at the National Ignition Facility (NIF) are of great scientific significance as they achieve for the first time an amplification of nuclear fusion energy of more than unity. This is a major scientific milestone.

“The international scientific community is working on different alternatives (inertial and magnetic confinement) with varying degrees of development towards the practical realisation of nuclear fusion energy. The degree of integration of science and technology towards a nuclear fusion reactor differentiates the results of magnetic confinement (JET-2022) and inertial confinement (NIF-2022).”

No conflict of interest declared.