Probably the most exciting result in nuclear fusion in recent history occurred at the US National Ignition Facility (NIF) in December 2022, when, for the first time, experimenters attained more energy (1.5 times more) out of the experiment than was put in. That achievement marks the realisation of ignition in nuclear fusion, the process that generates energy when molecules combine, rather than break apart (known as nuclear fission). It is the best demonstration so far that we might well be able to actually use fusion for power on Earth.

Where will the next big advance come from? It may not be the huge public-sector labs, but from one of the many small nuclear fusion organisations funded by private investors. It’s certainly true that private funding for fusion is growing, and this is a recent phenomenon. Almost two-thirds of the total funding for members of the 38 members of the Fusion Industry Association (FIA), amounting to about $4bn, has come in only the last few years, reports FIA CEO Andrew Holland – and, he adds, most of that was before December 2022, so was not sparked by the NIF news, either.

What could possibly attract a private investor to a such a remote corner of particle physics? It’s not like the field is new. Fusion dates back to the 1950s, but since then fusion results have been notoriously difficult to achieve, primarily because fusion reactions only occur at immense pressures and temperatures where matter becomes plasma: a hot gas, like lightning.