First Light Fusion Publishes Plausible Path to High Gain, Unlocking Cheap Fusion Energy
• First Light Fusion has presented the first reactor-compatible path to “high gain” fusion which would drastically reduce the cost of this limitless clean energy source.
• Gain (energy out divided by energy in – the efficiency of the fusion reaction) is *the* critical parameter in determining the cost of fusion energy.
• Models show that the company’s new concept for high gain fusion – called FLARE – could potentially access an extraordinary gain of 1,000, compared to today’s experimental level of 4 and an order of magnitude higher than other proposed inertial fusion energy (IFE) schemes.
• First Light has published a detailed white paper outlining its amplification technology and a new, complementary power plant approach – with the paper having been strongly endorsed by renowned physicists.
First Light Fusion (FLF), the UK’s leading IFE company, has today published the first commercially viable, reactor-compatible pathway for high gain inertial fusion – a critical step toward delivering affordable fusion energy at scale, an ambition often hailed as the ‘Holy Grail’ of energy.
In its white paper published today, the University of Oxford spin-out has outlined a novel and scientifically grounded approach to fusion energy called FLARE – Fusion via Low-power Assembly and Rapid Excitation. While the conventional IFE approach is to compress and heat the fuel at the same time to achieve ignition, FLARE splits this process into two: first compressing the fuel in a controlled and highly efficient manner and then using a separate process to ignite the compressed fuel, generating a massive surplus of energy, a concept known as “fast ignition”. Though this has long been researched, it is now made practical for the first time using First Light’s unique amplification technology.
FLARE leverages over 14 years of First Light’s inertial fusion experience and their unique controlled-amplification technology, creating a system capable of reaching the high gain levels needed for cost competitive energy production. This new approach would underpin the design for commercial reactors that can be based on much lower power systems that already exist today, opening up an opportunity for partners to build those systems, using FLF’s technology as the fuel, and to roll it out worldwide.
Gain – when more energy is converted from the reaction than energy delivered to the fuel – has long been the missing link to full-scale commercial fusion. The current record gain level stands at 4, achieved at the U.S. Department of Energy’s National Ignition Facility (NIF) in May of this year. The FLARE concept, as detailed in today’s white paper, could produce an energy gain of up to 1,000. FLF’s economic modelling suggests that a gain of at least 200 is needed for fusion energy to be commercially competitive, while a gain of 1,000 would enable very low-cost power.
The FLARE model offers a cheaper development pathway and drives down the expected cost of a fusion power plant: an experimental gain scale facility is expected to cost 1/20th that of NIF (the only facility that has achieved gain globally) and could be built using existing, proven technologies. Due to the lower energy and power requirements provided by the FLARE technology, future commercial power plants would have significantly lower capital costs than other plausible IFE schemes, with lower complexity and core components such as the energy delivery system costing 1/10th of the capital cost of previous fast ignition schemes. The lower pulse rate (enabled by the high gain) could also lower the operating costs. Since a pulsed system plant can adjust its output, it can also provide flexible, low-cost electricity to support modern grids which utilise a high level of intermittent renewables.
By building on existing technology, First Light’s approach takes the brakes off inertial fusion deployment as it has the potential to leverage existing supply chains, significantly reduce capital expenditure, speed up planning approvals and reduce regulatory hurdles in the deployment of commercial fusion plants.
First Light’s new FLARE approach has received strong backing from prominent plasma physicists, including Jeremy Chittenden, professor of plasma physics and co-director of the Centre for Inertial Fusion Studies at Imperial College London.
Mark Thomas, CEO of First Light Fusion, said: “This is a pivotal moment not just for First Light, but for the future of energy. With the FLARE approach, we’ve laid out the world’s first commercially viable, reactor-compatible pathway to high gain inertial fusion – and it’s grounded in real science, proven technologies, and practical engineering.
“A pathway to a gain of 1000 puts us well beyond the threshold where fusion becomes economically transformative. Through our approach, we’re opening the door to a new industrial sector – and we want to bring others with us.”
Dr Robert Trezona, Partner, Cleantech at IP Group, said: “The FLARE concept and its development pathway are landmark endorsements of First Light’s asset-light business model, paving the way, through partnership, to commercially viable nuclear fusion – a clean, near-infinite energy source. This breakthrough concept underscores the company’s scientific prowess and focus on developing low-cost pathways to abundant clean energy, positioning it – and the UK – at the forefront of a trillion-dollar market. We first backed First Light in 2011 and are proud to have supported its journey. This new concept shows that the company can continue to do amazing things in fusion energy.”
Lord David Willetts FRS, former Science minister and Chair of the Foundation for Science and Technology, said: “Fusion has often been dismissed as always 30 years away. That cliche fails to recognise how much real progress is being made, especially here in Britain. First Light Fusion has now shown a credible pathway to viable commercial fusion. The challenge now is to ensure the UK leads the rapid development of this technology.”
Professor Jeremy Chittenden adds: “First Light Fusion’s unique FLARE approach combines number of well-established concepts, each of which has been the subject of extensive study within US national laboratories. What makes First Light’s approach different is the way in which these concepts have been combined. In addition, the adaptation of First Light’s proven amplifier technology to cylindrical implosions means that the required fusion conditions can be realised using low voltage pulsed power, significantly reducing the cost of both the driver and the fusion targets.”
ENDS
Notes:
Technical background – Understanding gain: Gain is the ratio of energy output to energy input in a fusion reaction – the critical metric determining commercial viability. Current world record stands at 4x gain, achieved at the US National Ignition Facility (NIF) in May 2024. First Light’s FLARE concept models suggest gains of up to 1,000x, with economic analysis indicating gains of 200+ are needed for commercial competitiveness.
Commercial Applications and Scale: First Light’s FLARE approach targets building 400MW reactors – powerful enough to supply electricity to a city the size of Coventry (population ~345,000) while being compact enough to integrate seamlessly into existing power grids. The technology is particularly suited to powering energy-intensive AI data centres, which require reliable baseload power but face increasing restrictions on large-scale infrastructure development and lengthy grid connection timelines.
FLARE vs. Other Fusion Approaches
• Inertial Fusion Energy (IFE): Compresses fuel pellets using lasers or pulsed power to achieve fusion in brief bursts
• Magnetic Confinement Fusion (MCF): Uses powerful magnetic fields to contain hot plasma for sustained fusion reactions
• FLARE Innovation: A new concept for IFE that separates fuel compression from ignition (like a spark plug), using lower-power systems than conventional IFE
Comparison with major fusion projects
• ITER: International project in France, aims for first plasma 2034, commercial power decades later
• NIF: US facility that achieved current 4x gain record, cost $5.3B including upgrades
• STEP: UK government’s flagship fusion programme, targeting prototype plant by 2040 at West Burton
• First Light’s timeline: Commercial demonstration potentially by mid-2030s using $100M-$200M facility
Cost comparisons estimates
• FLARE demonstration facility: $100M-$200M ($2 per Joule stored energy)
• High-intensity pulsed power equivalent: $300M-$600M ($6 per Joule)
• NIF laser facility: $5.3B ($13 per Joule)
• Natural lithium per reactor: $70M vs. $143M-$451M for enriched lithium alternatives
Global fusion market size: The global fusion energy market is projected to reach $1 trillion by 2040, according to various industry analysts. Private fusion companies have raised over $5 billion globally since 2021, with significant increases following breakthrough results at facilities like NIF. Goldman Sachs estimates the fusion market could be worth $1 trillion annually by 2050, while others project the total addressable market could reach $40 trillion over several decades as fusion replaces fossil fuel infrastructure globally. The Commonwealth Fusion Systems alone has raised over $2 billion, indicating substantial investor confidence in commercial fusion potential.
UK Fusion funding context: The UK Government announced record £2.5B investment in fusion energy in 2024, primarily focused on magnetic confinement fusion (MCF) through the STEP programme. Private fusion companies globally have raised over $5B in recent years, with increasing investor interest following NIF’s breakthrough results (IFE).
Scientific validation: The white paper and FLARE approach have been endorsed by Professor Jeremy Chittenden, Professor of Plasma Physics and Co-Director of the Centre for Inertial Fusion Studies at Imperial College London. Additional expert commentary available on request.
Strategic Advantages: The FLARE design generates excess tritium – one of the rarest isotopes on earth – helping secure long-term fuel supply for future fusion reactors and addressing a critical industry bottleneck. Combined with faster development pathways using existing technologies, this could give the UK a critical advantage in delivering the first commercial-scale fusion reactor.
Industrial applications beyond energy: First Light’s pulsed power technology has applications in:
• Defence systems and materials testing
• Aerospace shock compression technologies
• Advanced materials research and development
• High-pressure physics research
