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M3 experiments demonstrate fuel compression using a simpler, lower power driver, marking an important step towards commercially viable high-gain inertial fusion

• M3 experiment validates FLARE’s core approach to compressing fusion fuel to high density
• Target-led compression reduces the power and complexity required from the driver
• Simpler, more robust systems could significantly reduce the cost of commercial fusion
• The result reduces a key technical risk as First Light moves towards integrated FLARE experiments

First Light Fusion has demonstrated the key fuel compression principle underpinning FLARE, its proprietary  approach to inertial fusion, in a series of experiments on M3, the company’s in-house pulsed power facility.

FLARE separates the two main steps needed for fusion: first compressing the fuel, then rapidly igniting it. Much like an engine compresses fuel before ignition, FLARE first assembles the fuel to high density before delivering a separate, rapid burst of energy to trigger fusion. The M3 experiments validate the first of these stages: compressing fuel to high density using a simple, lower power driver.

Why does this matter?

One of the central challenges in fusion is cost. The machines typically used to compress fuel must deliver enormous bursts of energy with exceptional precision. Repeating that process places significant stress on components, increasing operational and capital costs due to the risk of failure, maintenance requirements and downtime.

FLARE takes a different approach.  Its multi shell target is designed to control much of the compression process itself, turning a relatively simple electrical pulse into a carefully timed series of shock waves. These progressively compress the fuel to high density without prematurely heating it, reducing the peak power and complexity required from the driver.

By shifting more functionality into the target, FLARE is designed to enable a simpler, more robust driver, reducing component stress, maintenance and downtime. Reducing the power, complexity and cost of the driver is central to First Light’s approach to making fusion commercially viable, and First Light estimates that the FLARE compression driver could ultimately cost an order of magnitude less than comparable inertial fusion systems.

The platform demonstration is a major technical milestone achieved following the company’s £25 million fundraise earlier this year. The experiments were not designed to demonstrate ignition or fusion gain, but to isolate and test this core compression principle. The next phase will build on this validated compression platform, moving towards fusion relevant fuel conditions and then integrated experiments combining compression with the rapid heating needed to trigger fusion.

Mark Thomas, Chief Executive Officer at First Light Fusion, said:

“This experiment validates a central principle of FLARE: that we can simplify the machine by putting more functionality into the target. Demonstrating controlled compression on M3 is an important step in reducing risk on our path towards commercially viable fusion energy.”

Prof. Jeremy Chittenden, Chair of First Light Fusions’ Science Advisory Board, Professor of Plasma Physics and Director of the Centre for Inertial Fusion at Imperial College, said:

“First Light Fusion’s demonstration of the compression of materials to very high pressures, using multi-shell liners on a low voltage generator, represents a significant step on the path to validating the science behind the FLARE fusion concept.”

A step towards integrated FLARE experiments

The result materially reduces technical risk in FLARE’s staged development programme. It supports the hypothesis that lower power and therefore potentially lower cost machines can drive the first compression stage, while the target provides the pulse control needed to assemble the fuel.

It also advances First Light Fusion’s work on manufacturable multi-shell liners and is an important experimental step towards integrated experiments and a future high gain demonstration.

 

Notes to editors

About FLARE
FLARE (Fusion via Low-power Assembly and Rapid Excitation) is First Light Fusion’s inertial fusion architecture. It separates efficient fuel compression from rapid ignition, reducing peak power requirements and enabling a simpler, more scalable system.

About M3
M3 is First Light Fusion’s purpose-built pulsed power facility in Oxford and the second-highest current active pulsed power machine in the world. It is used for implosion hydrodynamics experiments supporting the company’s inertial fusion target validation programme.

About First Light Fusion

First Light Fusion is an Oxford-based company making commercial fusion possible with FLARE, its two-stage fusion fuel system, while applying its unique capabilities to solve the hardest problems in space, defence and beyond.

Founded in 2011, First Light has spent 15 years building deep expertise across fusion physics, simulation, target design, precision manufacturing, and experimental validation. Its world class facilities, including pulsed power machines and the UK's largest two-stage gas gun, serve as multi use platforms driving both fusion development and broader high energy density physics research under extreme conditions.

In September 2025, First Light published its landmark research paper, ‘FLARE - A Bold Strategy to Unlock Fusion Power’, outlining the world’s first commercially viable, reactor compatible pathway to high gain inertial fusion, offering a simpler, more viable route to abundant clean energy.

For more information, visit firstlightfusion.com

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