Iterative processes

HERE is one way to squeeze energy from nuclear fusion: create and contain a roiling soup of ionised hydrogen atoms known as a plasma, and heat it to ten times the temperature of the sun’s core. Some of the fast-moving atomic nuclei will bash together with enough oomph to fuse. Gather the energy from fast-moving particles created in these collisions and you have a limitless (for hydrogen is abundant), comparatively clean energy source. It is an idea conceived in the 1950s, but yet to be born in a laboratory.

Here is one way that might make it happen: gather an international consortium of the fusion-minded, including the European Union, America, China, India, Japan, Russia and South Korea. Conspire to build a 23,000-tonne doughnut-shaped vessel called a tokamak, that is wrapped with 80,000km of superconducting wire, all to contain the plasma magnetically and, for the first time, produce fusion energy continuously. Call it the International Thermonuclear Experimental Reactor; shorten the name to ITER for better PR. And farm out the design to the seven “domestic agency” partners, each completely in charge of the procurement and production of their bit (they will all have to agree to any changes, though, as the design of this technological beast inevitably evolves).