UK firm presents pathway to commercially viable fusion power
United Kingdom-based First Light Fusion (FLF) has presented a path to the first commercially viable, reactor-compatible path to nuclear fusion that will reduce the cost of a clean energy source.
The company from Oxfordshire has come up with a white paper that explains the process of ‘high gain’ inertial fusion.
The new approach is called Fusion via Low-power Assembly and Rapid Excitation (FLARE) as per the company’s white paper.
The conventional inertial fusion energy (IFE) technique compresses and heats the fuel at the same time to reach ignition. The FLARE process decouples the steps; there is first compression of the fuel in a controlled manner, and then a separate step to ignite the compressed fuel. The process generates a huge surplus of energy in a concept known as ‘fast ignition’.
First Light Fusion’s FLARE process
Instead of relying on high-power lasers, FLF uses cylindrical targets with a dense, opaque pusher to compress the fuel using modest input energy.
Losses are reduced, confinement is improved, and ignition is triggered by an auxiliary source such as a short-pulse laser or pulsed power system. The pulsed power used by FLARE offers a low-cost alternative to lasers. The low-voltage design removes the complexities that have previously limited pulsed power-driven IFE.
The fusion reaction is carried out in a liquid lithium pool, which is dynamically structured with inert gas. “This design absorbs neutrons, breeds tritium, captures heat, and protects the reactor walls without the need for complex solid structures,” the company says.
The company says that its concept is based on years of insights and research to provide an economical approach to ignition, burn, and high-gain from a low-power driver.
It will now focus on validating each project component on existing experimental facilities. The company will now model, design, and prototype the targets to build the scientific and engineering case for its first demonstration reactor.
Viable nuclear fusion energy
The company says that its new high-gain nuclear fusion concept could achieve an extraordinary gain of 1,000, compared to today’s experimental level of four, and an order of magnitude higher than other proposed inertial fusion energy (IFE) schemes.
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 nuclear fusion.
The record as of date stands at four, which was achieved at the U.S. Department of Energy’s National Ignition Facility (NIF) in May 2025.
The company’s modeling suggests that a gain of at least 200 is needed for fusion energy to be commercially competitive. Therefore, a gain of 1,000 – once realized – could lead to very low-cost nuclear fusion energy.
Moreover, the FLARE model 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.
“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,” said Mark Thomas, CEO of First Light Fusion.
“A pathway to a gain of 1,000 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.”