It hopes to be able to build a 150 megawatt pilot power plant in the 2030s and is working with UBS, the Swiss bank, on its development plans.
Spun out of Oxford University in 2011, First Light Fusion is among the front-runners in the global race to produce energy through nuclear fusion. It offers the prospect of abundant, clean energy by replicating the process that fuels the sun.
Work on producing energy from nuclear fusion has been underway for decades but has always seemed a distant prospect given the technical challenges involved.
Nuclear fusion requires fusing two atoms at extremely high temperatures, which is extremely difficult but can be done using either magnetic fields or by compressing a fuel pellet.
First Light Fusion’s approach is based on the latter, and involves using a 22-metre gas gun to fire a 100g projectile at 6.5km a second – about 20 times the speed of sound – at the pellet containing tritium and deuterium.
The company ultimately wants to develop power plants in which the process would be repeated every 30 seconds, with every pellet, each a few millimetres in size, generating enough energy to power the average UK home for more than two years.
It believes it could eventually produce power for less than $50 (£38) per megawatt hour, making it competitive with renewables.
In February the company raised $45m from backers including the Chinese tech giant Tencent.
Its breakthrough comes after researchers at the JET laboratory in Culham, near Oxford, in February set a record for the amount of fusion energy produced.
Researchers achieved 59 megajoules of sustained fusion energy, well above the 22 megajoules achieved in 1997, albeit only enough to boil about 60 kettles.
By comparison the amount produced by First Light Fusion was very low, but the milestone is in achieving fusion at all using its new process.
Professor Yiannis Ventikos, co-founder of First Light Fusion and head of UCL’s mechanical engineering department, said: “This pursuit of practical and affordable fusion will give us the clean and abundant baseload power that we so desperately need in our effort to address – and hopefully reverse – global warming.”