Milestone in nuclear fusion puts power of stars within our reach

Perhaps the most significant recent science news was in a relatively subdued report from the BBC. The story noted that "researchers at a US lab have passed a crucial milestone on the way to their ultimate goal of achieving self-sustaining nuclear fusion".

Scientists at the National Ignition Facility (NIF) in California had focused laser beams to heat and compress a small pellet of hydrogen fuel and achieved a world first: more energy was released through the fusion reaction than was absorbed by the fuel.

Perhaps this brings us a step closer to harnessing the power of stars, where extreme temperatures and pressures cause atomic nuclei to combine forming larger elements and with slight mass loss accompanied by intense energy release. These fusion processes can start with hydrogen, helium and lithium that formed in the big bang, and evolve elements as heavy as iron - after which you need a supernova to unleash the forces needed to combine nuclei and supply energy to create heavy elements.

Here on earth, there is potential for deriving virtually unlimited clean energy from fusion power, without the severe downsides of nuclear power based on splitting atoms, such as radioactive waste and the chance of meltdowns. But the lower gravity makes even combining hydrogen nuclei extremely challenging. Hydrogen bombs developed in the early 1950s involved regular nuclear explosions to initiate fusion: hardly suitable for your neighbourhood power station.

Several projects are under way to discover ways to harness fusion power, which is akin to a holy grail of nuclear physics. "Fusion is a nearly ideal energy source - essentially inexhaustible, clean, safe and likely available to all nations. When proven practical, it will transform our energy future," Stewart Prager, director of the US Department of Energy's Princeton Plasma Physics Laboratory, wrote in a commentary on The New York Times website last year.

Culham Centre for Fusion Energy, the UK's national laboratory for fusion research, announces careers in fusion with the slogan "Come to work to change the world". Work there focuses on initiating fusion within plasmas - extremely hot mixes of atomic nuclei stripped of their electrons - contained within magnetic fields. The devices used are tokamaks, devices shaped like giant doughnuts that were invented by Soviet scientists in the 1950s.