BBC News: How to build a star on Earth.
Nuclear fusion is nature’s power source. From the Sun to the most distant stars, the energy that lights up the Universe is released by sticking hydrogen nuclei together to make helium. Since hydrogen is the most abundant element in the Universe, it seems sensible to ask whether we might endeavour to do the same and power ourselves out of our serious energy crisis by building stars on Earth. The problem of course is that stars are big and hot; the Sun is the size of a million Earths, and burns six hundred million tonnes of hydrogen fuel every second. The temperature at its core is 15 million degrees, and this is barely enough to allow fusion to take place at anything other than a snail’s pace.
Despite the obvious difficulties, however, the UK has hosted a working nuclear fusion reactor in Oxfordshire for the last three decades. Jet, the Joint European Torus, routinely heats a cocktail of different forms of hydrogen known as deuterium and tritium to well over one hundred million degrees and initiates nuclear fusion at a rate far in excess of that in the centre of the Sun.
The University of Surrey has an industrial year program, where students complete two years of their degree, then spend a year working in their field, then return to finish off the degree. My year was spent at the National Grid Company, Tom’s was spent at Jet. Fusion requires serious magnetic containment and brutal temperatures so hot you strip the electrons off the atoms, leaving a plasma whirling around the toroid reactor. The reactor is shaped like a donut, but more precisely circular.