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  • On December 13, 2022, the U.S. Department of Energy (DOE) and DOE’s National Nuclear Security Administration (NNSA) announced the achievement of fusion ignition at Lawrence Livermore National Laboratory (LLNL) — a major scientific breakthrough decades in the making that will pave the way for advancements in national defense and lays the groundwork for inertial fusion energy as a potential energy source for the future. On December 5, a team at LLNL’s National Ignition Facility (NIF) conducted the first controlled fusion experiment in history to reach this milestone, also known as scientific energy breakeven, meaning it produced more energy from fusion than the laser energy used to drive it.   


    Mark Herrmann is the Program Director for the Weapon Physics and Design (WPD) Program at LLNL. In this role, Herrmann leads LLNL’s efforts to strengthen the U.S. nuclear deterrent by advancing the understanding of nuclear weapons physics and design. This includes the physics design, assessment, and certification efforts.  He also leads weapon science research and development, including focused experiments, integral hydrodynamic and subcritical experiments, high-energy-density (HED) experiments at the National Ignition Facility (NIF), and modeling and simulation of these experiments using NNSA’s high-performance computing capabilities.


MODERATOR:  Hello, and welcome to the Foreign Press Center’s briefing on the recent fusion ignition breakthrough achieved at the Lawrence Livermore National Laboratory.  Joining us today is Mark Herrmann, the program director for the Weapon Physics and Design program at Lawrence Livermore.  My name is Wes Robertson and I’m the moderator for today’s briefing. 

And now for the ground rules.  This briefing is on the record.  We will post a transcript and the video of this briefing later today on our website, which is  Please make sure that your Zoom profile has your full name and the media outlet you represent. 

Mark will now give opening remarks, and then we’ll open it up for questions.  Over to you, sir. 

MR HERRMANN:  Super.  Thanks.  And very happy to be here to explain a little more about the exciting results that we reported on last month.  I want to show you a few slides to kind of highlight some of the elements of this advance, and so I’m going to pull those up right now. 

And of course, this is – I’m representing the work of a very large collaboration with multiple national laboratories and scientists, engineers who have worked on this for a very long time.  And I’ll talk a little bit more about that, so – very happy to do that.  

So as we announced back in December, an experiment on December 5th on the National Ignition Facility – and I’ll describe what that is in just a little bit – exceeded the threshold for fusion ignition.  This is – what that means if for the first time ever in a laboratory, we were able to put in a certain amount of energy into the experiment, and then the amount of energy that was released by fusion was greater than the amount of energy we put in, demonstrating that fusion is – in the laboratory is a possibility for generating very extreme environments and potentially someday generating more energy out than goes in, and a potential path to a fusion power energy plant. 

We do this work to support our nuclear deterrent, and I’ll talk more about that.  And so it’s also a significant advance for our ability to maintain our deterrent without the need for further underground nuclear weapons testing.   

On the right here, I show some data from the National Ignition Facility on a series of experiments that have been taking place over the last 11 years on that facility.  The facility came on in 2009, and we’ve been doing fusion experiments as part of the work we do on the facility to support our deterrent and maintain it without the need for further underground testing.  But about 15 to 20 percent of the experiments we do on the facility are related to fusion, and what I show here is the fusion output in each of those experiments – almost 200 experiments in this case – over that last 11 years.  I also show where the laser energy is, so you can see that while – when we started the fusion outputs were very low.  We were able to make progress on that and eventually made a significant advance a year ago, and then again in this experiment just last month generated more fusion energy than the laser energy we put in.   

And so now I’m going to describe a little bit about that and what some of the implications are from that experiment.   

First, I want to describe the facility.  This is a picture, a cutaway picture, of the National Ignition Facility.  The facility itself is at Lawrence Livermore National Laboratory.  It’s the size of, roughly speaking, three football fields.  You can put three American football fields on the roof of the facility.  And underneath that roof are 192 laser beams.  Each of these laser beams is quite energetic; it’s one of the most energetic lasers in the world individually. And all 192 are by far the most energetic laser that’s operating in the world today.  And all of those lasers in that three football fields get concentrated onto targets that are about the size of a pencil eraser.  And that’s what’s shown here.   

So all of the laser energy from three football fields goes into that little, tiny target for a very short amount of time.  And in many of the experiments, they create X-rays, and those X-rays radiate and compress a little tiny capsule about half the size of a peppercorn, and – which contains fusion fuel.  And in doing that, it – we squeeze the fusion fuel up to extreme conditions and are able to study the fusion process in the laboratory. 

So the actual configuration of these experiments is what we call indirect drive.  We actually – so this shows you the laser beams coming into our little target that I just showed you a picture of.  The lasers heat up this little gold can, and – that we call a hohlraum.  It creates X-rays; those X-rays bathe that capsule uniformly, and we squeeze.  The outside of the capsule blows off, the inside of the capsule goes in.  At the very inside of the capsule, we have deuterium and tritium.  And eventually, as it’s rocketing in, it stops, it stagnates; temperatures and pressures go enormously high, the temperatures get up to hundreds of millions of degrees, the pressures go up to pressures greater than the pressure at the center of the sun.  So very, very extreme conditions. 

And then we get into a race.  So that very high pressure, very high temperature plasma wants to fall apart, it wants to lose energy, it wants to cool.  But the fusion reactions that are taking place want to deposit heat.  The fusion reactions are – related to the fusion reactions that take place in the sun.  They create energy.  And so there’s this balance between the heating from the fusion reactions and the cooling.  And if we can get it a little bit hotter, we get more fusion reactions.  And if we get it a little bit hotter, we get more fusion reactions.   

And so if you can win this competition between heating and cooling, you can actually get a runaway reaction, which we call fusion ignition, and that’s what happened for the first time in this experiment last month.  This is a long-term effort, and I’ll talk a little bit about the history as well in just a couple slides. 

So why are we so interested in this?  So one of the reasons is that these very, very extreme environments in the – being able to study these very extreme environments in the laboratory enables us to understand and maintain our nuclear deterrent.   

Kind of to give you a sense of the scale of the extremities of these experiments, I want to kind of go through some numbers here.  So the entire NIF laser – those 192 beams, the size of three football fields – they can generate about 500 trillion watts of power.  So you’re used to power in terms of 100 watt lightbulb, or we can talk about the electrical generating capacity of the United States.  It’s about 1 trillion watts.  So at any point in time, all the electricity from all the power plants in the U.S. is about 1 trillion watts.  So this laser generates 500 times that and deposits it into that little tiny target, but it only does it for a very short amount of time – four billionths of a second.  

And when the laser goes into that target, it heats it up to a few million degrees.  But that’s not extreme enough to create the fusion conditions.  In fact, we have to squeeze that fusion fuel up and reach temperatures – in this experiment, we reached temperatures as high as 130 million degrees, so very, very high temperatures.  The plasma gets very small.  It’s about the size of a human hair at the most extreme conditions.  And when we – in this experiment, the fusion reactions took place in about one-tenth of a billionth of a second.  So – and the power that was generated, the fusion power that was generated, is greater than 30,000 trillion watts.  So much more than the power that was generated by the laser, very extreme.   

To kind of put it in perspective, the entire – all the sunshine hitting the Earth at one point – at any point in time is about 170,000 trillion watts.  So for a tiny amount of time, this little thing the size of a human hair in our laboratory generated about a fifth the power of all the sunlight hitting the Earth.  So it’s incredible extreme conditions.  Of course, we generate those and study those because that is the same level of energy and power that’s operating in our nuclear weapons.  

We’ve been working on this for a very, very long time, starting in the 1950s with the first ideas, and shortly thereafter the laser was invented in 1960.  And our laboratory then began building a series of ever bigger lasers to try and achieve this – these very extreme conditions required to do fusion ignition.   

Along the way, we were maintaining our nuclear deterrent through the 1990s with underground nuclear weapons testing to maintain the confidence in our deterrent.  But in 1992, we made the decision to stop our underground nuclear weapons testing and we stood up something we call the Science-Based Stockpile Stewardship Program to maintain our deterrent and our confidence in it without the need for further underground testing.  And that involved capability – development of capabilities like high-performance computers, experimental testing facilities, including building the National Ignition Facility, which allows us to access those extreme regimes that are found in nuclear weapons.  

Along the way, we did many different scientific experiments.  NIF has done almost 4,000 different experiments and across many fields of science.  It’s not just fusion.  We study the behavior of material at very high pressures and temperatures.  We study the transport of radiation in complicated geometries.  There are many different elements of physics we study with the NIF, and there’s almost a thousand scientific publications that have been published. 

But we always were focused on that goal of ignition, and that’s why we named the facility the National Ignition Facility.  And so a year ago, we made a significant advance to 1.3 megajoules – not as much as the laser, but getting close to the amount of energy with the laser.  And then most recently in December 5th we got that 3.15 megajoules.   

Now I think there’s a lot of discussion around these experiments.  I just want to kind of put a little bit of context.  As I’ve mentioned many times, right, our goal in these experiments is to understand fusion so that we can maintain our nuclear deterrent.  Fusion is a process that’s in our modern nuclear weapons, and we have to understand it to maintain the deterrent.  It’s also an incredible scientific challenge to study fusion.  It requires the – getting material up to very extreme temperatures and pressures, and so we – it’s just a scientific grand challenge to achieve these extreme conditions.   

And fusion has a potential to be a carbon-free baseload energy source for humanity as we go into the future.  And right now, having more approaches, different ways of being able to provide carbon-free baseload energy in the future is something that would be great to have.  We don’t have just one silver bullet that’s going to solve what our long-term energy – carbon-free energy needs are for the planet and so this is one possible approach to that.  

Now, sometimes people look at it and say, well – and again, this was an experiment supporting our nuclear deterrent, but it does have implications for energy security if you could turn it into an energy plant.  Some people look at it and say this is about national security, but it’s also about science, right, so it’s really about all of these things.  It’s actually what makes in my mind fusion such an interesting thing to study because it has implications for all these different areas and certainly why we’ve been working on it for so long – why it’s been such a long-term goal for our laboratory.  So I think it’s a – it’s one of those things that it’s not just one or the other, but it touches on all of these things.   

Finally, there’s some question – okay, how would you pursue energy based on this, if you were – if you were going to do that?  This is something actually that the U.S. National Academy of Sciences has studied.  There was a report released in 2013, looking at both what research programs should be done in inertial fusion energy.  And what they said at that time is that the time for really pursuing that would be after fusion ignition was achieved, and obviously we’ve achieved that.  So that’s something that – that report is very relevant to where we are today in terms of pursuing inertial fusion as an energy source.    

Just a little bit about the high-level idea of how that would work, we do one experiment in maybe every 24 hours on the NIF depending on the complexity the experiment.  Sometimes we can do a few experiments in a day.  The way a power plant would work is you would inject targets at as much as 10 times a second, so a long way from where we are today, right – we do one experiment a day.  That would be almost a million experiments a day if you were doing 10 times a second.   

Our laser pulls over 300 megajoules off the grid to do these experiments and then converts that into 2 megajoules of laser light and that gave us 3 megajoules of fusion energy.  So right now we’re not winning, we’re losing in – from the – that overall energy balance.  But there are lasers that are much more efficient than the NIF, so you would have a laser that was maybe – would only pull a few megajoules off the grid in order to generate the energy to create these fusion reactions.   

You can also get a lot more energy out than three megajoules.  Our goal – our research program on NIF now will be about how do we get many more megajoules out than the three megajoule experiment.  Understanding how we basically lit the match that enabled this fusion ignition will enable us to go farther into the future.  So you’ll need a target that could get – generate more gain as well.  But the idea would be something like an internal combustion engine where you would shoot a new target in, you would create the fusion reaction, you would release energy, you would capture that heat as heat, and then you would use that to generate electricity.   

So that’s the basic idea.  It’s many orders of magnitude beyond what we’ve been able to demonstrate today, but this is a really exciting and significant step that’s never been done before in any laboratory, which is why we’re excited about it.   

So just to come to a conclusion there and open it up to questions, this is the work of many, many hundreds – really thousands of people.  This is one picture of the team from a few years ago, many institutions working together.  It’s really a testament to scientific and engineering precision, control, understanding, and determination and grit, right, because there were many steps along the way where this was harder than we thought it was going to be.  It took longer than we thought it would, and people who thought we would never, never succeed.  And so I think it is really something we’d like to celebrate as a great accomplishment, an example of innovation and determination, and enabling all sorts of exciting new science to support both our national security and hopefully someday our energy security as well.   

So with that, I’m happy to take any questions.  

MODERATOR:  Okay.  Thank you so much for that fascinating presentation and congratulations to you and your team.  That’s – it’s amazing.  So if you have questions, please go to the participant field and virtually raise your hand.  We’ll call on you, and you can unmute yourself and ask your question.  You can also submit questions in the chat box.  If you’ve not already done so, please take the time now to rename your Zoom profile with your full name and the name of your media outlet.   

I don’t see any hands raised yet, but there was one question that was submitted in advance.  This is from Antonella Ciancio from Il Messaggero, Italy.  She asks, “What applications will this important breakthrough have in the development of weapons and defense systems?”  

MR HERRMANN:  Yeah, so as I mentioned, we have this responsibility to maintain our nuclear deterrent without using underground nuclear weapons testing.  And we haven’t done an underground nuclear weapons test for almost 30 years.  But nuclear weapons are complicated, and we – when we stopped our underground nuclear weapons testing, we didn’t understand all the elements that go in – that go into it.   

And so we’ve been embarking on a program for this entire time to understand the science of our nuclear weapons so that we can maintain them so that as they age, we understand how we have to respond to things we find as the weapons are aging, as we currently are modernizing our nuclear deterrent so that it will be safe, secure, effective, and reliable into the foreseeable future.  And these fusion experiments allow us to create the very extreme conditions that allow us to really understand all the elements of the science that are going on in our nuclear weapons.  So it’s a key advance in enabling us to maintain our deterrent. 

MODERATOR:  Thank you.  I don’t see any questions still, so I would just ask one myself:  What are sort of the next steps in terms of you made this big breakthrough?  What are sort of the timeline from here and what are sort of the next steps you all will be focusing on? 

MR HERRMANN:  Yeah, so we do, again, about 400 experiments a year.  About 20 of them are experiments of this type, and so we’re working right now on how do we incorporate what we’ve learned from this experiment to both repeat this experiment but be – go beyond it.  We have plans to make the laser even more energetic.  We have plans to make the little targets that the laser hits even better.  And we want to really explore how do we get even more energy out than the three megajoules – can we get five or 10 megajoules out, which the more we get out, the more extreme the conditions, the better the fidelity of the experiments we’re doing. 

We also want to understand how do we make it easier, right – if you were ever going to do energy, you’d like to not have to build a laser the size of three football fields.  So how – if we could really understand it, once you have a tool and it’s working, then you can think about oh, can I take a shortcut here, can I take a shortcut there.  How do I drop the requirements and make it easier to do, right, so that’s another thing that we’re trying to do. 

And then we’re using the output – this tremendous blast of X-rays and neutrons that come from these experiments – to study their interaction with materials for our nuclear weapons applications.  So we also are going to use the output of this to do further studies as well. 

MODERATOR:  Thank you very much.  I do see we have a question from Véronique Le Billon from Les Echos, France, if you’d like to go ahead, unmute yourself, and ask your question now. 

QUESTION:  Yes, hi.  Do you hear me, yeah?  It’s good? 


QUESTION:  Thank you – yeah, thank you very much for doing this.  We know that there is another technology in fusion in France, for instance with ITER, and there are many – well, some private companies were also testing magnetic fusion.  Can you help me understand what your discovery and breakthrough implies for these other technology in fusion?  And I mean, would it speed up their research and discoveries too?  Merci. 

MR HERRMANN:  Yeah, so thanks for the – it’s a great question.  Let’s see.  I think fusion is really hard, right – I mentioned we’ve been working on it for 60 years.  There – but magnetic fusion research is also something that’s been going on for many, many decades, and again, it’s challenging because of these very extreme temperatures that are required for the fusion reaction to take place.  And so there are many benefits of understanding how do you handle and create a fusion system.  There are many similarities in terms of the materials you have to handle, the effects of the fusion reaction on the confinement system, and all those things.  So we do – and the way we diagnose what’s going on in our experiments.  And so there’s a lot of ties between the scientific communities that study inertial confinement fusion and magnetic fusion. 

But they’re also very different, right – magnetic fusion would work in a steady state configuration.  Basically you would just turn it on and it would keep running all the time, whereas ours – our approach would be a fundamentally pulsed approach, where you have to introduce a new target every time you want to generate some fusion reactions. 

And so the way I think about it is that this is a really hard problem.  Having multiple, diverse approaches to solving it is really critical because we don’t know what roadblocks any one approach may run into from a long term if you want to get to energy.  And so it’s good to have lots of different approaches, and I think the scientific advances that help enable this, like highperformance computing and better diagnostic and better manufacturing capabilities, all of those are helping both magnetic fusion and inertial fusion.  And there’s certainly an intense interest today in how could we move fusion even faster because of the urgency associated with finding new approaches to carbon-free energy. 

So I think the result both kind of gives confidence that all approaches are worth studying and can – and make progress, and also kind of diversifies the approaches that are being pursued for energy. 

QUESTION:  Thank you. 

MODERATOR:  I do see another question that was submitted via the chat function.  This is from Olukorede Yishau from The Nation, Nigeria.  He asks, “Most scientific breakthroughs come with negative effects.  What are the side effects of this?” 

MR HERRMANN:  Yeah, I think that’s a great question.  So, of course, we’re doing this work because we think of it as important, again, for maintaining our nuclear deterrent and potentially a path to energy.  Any fusion system, though, does have things that we have to be careful of, and we of course consider those very carefully, right?  So in the – when this blast is taking place, people have to be far away.  We have a – we have a facility and we have the doors and things like that that we have to close, and we keep people out of it, and we have to wait for a period of time before we go back into it.  So we’re very careful about that.  Safety is a very important consideration. 

People have looked at fusion and the potential it may have for proliferation.  We think that the concerns associated with that, that’s something that was studied before we built the National Ignition Facility to make sure that any concerns along the lines of proliferation were manageable.  I mean, the main concern is that fusion neutrons are very energetic and so they could be used to convert uranium into plutonium.  And so, but that would be managed if you had a fusion energy economy, and that’s something that the IAEA and other agencies are thinking about. 

I think – I’ve seen – again, we’re many decades away from putting power on the grid with this approach, but if you did have a lot more energy available to you, that could be good because we think that the biggest determination of how – the more energy that – there’s a strong correlation between energy usage and GDP per capita and people’s standards of living, so that’s a good thing if we could generate more energy.  But having unlimited energy may not be a great thing in terms of what the implications would be for the environment and things like that.  Again, I’d say we’re a long way away from that, but it’s something that people are thinking about as they work to develop fusion as an energy system. 

MODERATOR:  Okay, I have another question that was submitted.  It asks: “Do you work with other labs internationally?” 

MR HERRMANN:  Yes, absolutely.  So we have close collaborators in the atomic weapons establishment in the UK and the CEA in France.  In fact, France is building a facility that’s similar to our National Ignition Facility called the Laser Mégajoule.  So we have strong collaboration there centered around our defense missions.  But we also have university collaborators at institutions around the world who are interested in the very extreme environments that can be created in our laboratory, so we work with universities and labs all over the world. 

MODERATOR:  All right, thank you so much.  I don’t see any additional questions at this time, so we will go ahead and conclude our briefing.  I want to give special thanks to Mark for sharing his time with us today and on this fascinating topic.  And to those of you who participated, thank you very much and good day. 

U.S. Department of State

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