SPECIAL REPORT | FLARE
Creating gain in fusion
Fusion has long been described as the energy of the future, but by starting with an innovative target concept and working outwards, First Light Fusion aims to offer a new route to make fusion the energy of the present.
The FLARE approach first compresses the fuel to high densities and then uses a separate process to ignite it. Source: First Light Fusion
THE DESIGN OF A POWER plant based on Inertial Confinement Fusion (ICF) must not only ensure the systems are robust enough to withstand the rigors of repeated high- energy pulses but, critically, also achieve sufficient gain. A new study from University of Oxford spin-out First Light
Fusion presents a path to the high gain fusion technology which it says would drastically reduce the cost of fusion energy. This model is known as Fusion via Low-power Assembly and Rapid Excitation (FLARE). This paper notes that ICF requires enormous amounts of
energy to compress and ignite the fusion fuel, yet typically less than 1% of that energy actually couples to the target. The extent to which a fusion reaction produces more energy than is delivered to the fuel, known as gain, is therefore key. The current record gain for ICF, achieved in May 2025 at the US Department of Energy’s National Ignition Facility (NIF), is just four but according to First Light economic modelling, a gain of at least 200 is needed for fusion to be commercially competitive, while a gain of 1,000 could deliver power at exceptionally low cost. The FLARE concept is designed to achieve these gains of
up to 1,000 through a step change in the design approach. The crux of this approach is simplifying the driver, which are conventionally extremely powerful and require near-perfect precision. These requirements drive costs into the billions and stretch development timelines far beyond practicality. The FLARE approach shifts more of the performance burden onto the target while also designing a reactor that is inherently robust, scalable, and affordable.
18 | January 2026 |
www.neimagazine.com
Cutting driver energies The conventional ICF approach both compresses and heats the fuel at the same time to achieve ignition. This configuration requires precise symmetry, pulse shaping, and timing as the simultaneous heating opposes compression, increasing driver energy and power specifications. One method of reducing driver energy requirements is to decouple the compression and heating stages. This is the FLARE approach: first compressing the fuel in a controlled and highly efficient manner to high densities without forming a central hotspot and then using a separate process to ignite the compressed fuel by rapidly heated a small area using a short, intense pulse, typically delivered by a laser or charged particle beam. Carefully tailored compression of the fuel minimises its heating (and consequently pressure), making it easier to assemble to the high densities required for ignition. This approach – known as fast ignition –eliminates the need for ultra-precise implosion symmetry as no highly converged hotspot needs to be formed. It also removes the energy budget required to form a hotspot in pressure equilibrium with the surrounding fuel. First Light argues that the separation of the heating
and compression allows compressive work of the fuel to be maximised with (ideally) no increase in entropy. It emphasises this point, noting that minimising entropy represents a key efficiency of a particular fusion scheme and observing that the efficiency benefits of isentropic fuel compression have been recognised from the very beginnings of ICF research.
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