Set the controls for the heart of the Sun

The highly compacted core of the sun is a very hot place indeed.

In the star’s burning heart, hydrogen atoms collide at immense speeds. This welds them together and turns them into helium atoms, which each release a burst of energy that escapes into the solar system as light. It is a nuclear furnace, responsible for fuelling all life on Earth, that consumes a lot of hydrogen (600 million tons every second) at very high temperatures (over 15 million degrees C). As such, it’s the second-hottest place in the solar system.

The hottest place? Surprisingly, that’s rather closer to home: to be precise, the small English village of Culham, a few miles down the A4074 out of Oxford.
The reactor inside the Culham Science Centre, which is managed by the UK’s Atomic Energy Authority, recreates the reaction that occurs at the heart of the sun, only more intensely. Here, less than a gram of hydrogen is used, but it’s heated to 200 million degrees C by high-energy beams that are among the most powerful and lethal heating devices on Earth.

On start-up, when two 50ft white towers aim their barrel-sized particle cannons into the reactor, will it explode into a fireball and swallow our planet like a lump of coke in a blast furnace? Happily, no. When the reactor burns, the hydrogen becomes so hot that no physical container can cool or hold it; so the intense magnetic field holds the swirling vortex of superheated hydrogen in place. The reacting material is completely invisible – it radiates energy at frequencies the human eye can’t see – but as the reactor heats, sections of the wall become so hot that the tiles glow red.

Meanwhile, the incredibly intense particle beams consist of uncharged atoms flying at more than ten million metres per second. They would instantly vaporise anyone who stood in front of them. Even metal components melt in microseconds if they get in the way of the beams. So the towers are cooled with liquid helium, as well as water – 4,000 cubic metres are pumped through the system every hour.

And what’s it all for? Simply, the experiments at JET could pave the way for a scientific achievement on a par with putting a man on the Moon. JET has been able to initiate nuclear fusion at the touch of a button for decades – but the energy put in has always outweighed the energy harvested from the reactor.

Now, though, it’s being used as a test bed for a new reactor, ITER, which will generate electricity from fusion, using fuel found in ordinary seawater. Just one cubic kilometre of seawater contains enough deuterium – used as a nuclear fuel by JET – to generate more power than the world’s entire oil reserves.

Daily Mail