US lab repeats fusion breakthrough
For the second time in nine months the Lawrence Livermore lab in California has achieved what nuclear fusion scientists had previously tried and failed to achieve for 50 years. A laser shot trained on a tiny pellet of fusion fuel triggered a reaction yielding more energy than needed to start it. The laser (in fact 192 lasers) delivered 2.05 megajoules to the target for an output of 3.5. This is ignition. Repeatability is vital for an experiment to count as progress, but the caveats bear repeating. First, the 2.05 megajoules focused on the fuel was a tiny fraction of the energy needed to power up the enormously wasteful lasers. Second, the National Ignition Facility (NIF) at Lawrence Livermore can do one shot a day, but to use its inertial confinement technique to produce power commercially would take ten a second. Third, most fusion start-ups are using radically different technologies, none of which have yet achieved ignition. Still, the NIF is establishing that controlled fusion is possible. The rest is engineering.
Photograph: Lawrence Livermore National Laboratory