How to Build a Star

Nuclear fission is the ideal energy source of the future. Fission reactors are vastly more efficient than fusion reactors, use the harmless and abundant elements hydrogen and lithium, produce no greenhouse emissions and generate effectively zero dangerous waste. The only problem is that the nearest fusion reactor that can currently provide for our energy needs is 150 million kilometres away. We call it the Sun. A team of the ANU’s scientists and engineers, led by Professor John Howard (not that John Howard), is helping to fix that.

In southern France, an international mission is underway to construct the first economically viable fusion reactor, called ITER (Latin for “the way”). A fission reactor, whether natural or human made, releases energy by “fusing” light atoms rather than “splitting” heavy atoms. There are some differences between ITER and a star. The human-made reactor is contained in a doughnut-shape by electromagnetic fields within a metal chamber called a tokamak, rather than being contained in a sphere by its own gravity. ITER’s tokamak is contained within a seven story high, natural-disaster proof structure.

Both human-made reactors and stars are made from plasma that reaches temperatures of hundreds of millions of degrees celsius in the centre. Sometimes, turbulence causes powerful bursts of superheated material to escape the confined body of plasma. In the case of ITER, this could be dangerous.

There are a few reasons why these bursts of energy do not always melt holes through tokomaks, releasing the superheated plasma and destroying the Earth. It has to do with the amount of plasma in relation to the amount of metal forming the metal tokomak containing it, as well as the time it is in contact with the tokomak.

Yet, “meltdowns” are possible and it is important to prevent them, especially in such a large reactor. These bursts of energy and the temperature of the tokomak containing the plasma must be carefully monitored. The job of the ANU team is to design a system for ITER that will monitor this information. In June, Professor Howard will be meeting with the ITER team in France in preparation for this work.

It’s hard to tell whether fusion is really “the way” forward for our energy production needs. ITER will represent a theoretically “ideal” source of energy and be economically viable in itself, but it is really just the last experiment before commercial fusion reactors are designed. It will be decades at least before we see as many commercial fusion reactors as fission reactors. Solar panels and other renewable energy technologies are already springing up everywhere.

Personally, I think renewable energy technologies will dominate the near future. I’d still bet that fusion reactors will eventually be utilised in ways that we cannot yet imagine.

To learn more see www.iter.org and http://www.abc.net.au/radionational/programs/futuretense/the-quest-for-nuclear-fusion/6260938