Meeting of minds

UK research in nuclear fusion has received a significant boost with the creation of a Centre for Fusion, Space and Astrophysics at the University of Warwick.

Under the directorship of Sandra Chapman, who heads plasma astrophysics at Warwick, and Richard Dendy, who leads the theoretical physics group at UKAEA’s Culham Science Centre, the centre is being backed by a £5m Science and Innovation award from the Engineering and Physical Sciences Research Council.

Plasma physics is an essential part of the push to create a practical way of using nuclear fusion to generate power.

Two light nuclei – the heavy isotopes of hydrogen, deuterium and tritium – are heated to extremely high temperatures, about 100moC, and confined closely together using magnetic fields.

This causes the two nuclei to fuse, forming a helium nucleus and a neutron, releasing energy. At such high temperatures, the nuclei of the hydrogen atoms and their electrons dissociate and this gaseous mixture of free-charged particles is termed ‘plasma’.

The Joint European Torus, or Jet, at Culham has been in operation since 1983 and is the world’s largest fusion device that uses a magnetic field to confine the plasma.

Next experiment

‘Before Jet, there were serious question marks about whether fusion was scientifically feasible,’ said Dendy.

‘Those question marks have now almost all been removed. While some interesting physics issues remain, I can’t see any serious potential show-stoppers in plasma science.’

The next big experiment, the ITER magnetic confinement facility, is to be built in Cadarache, France. Again, it is based around a hydrogen plasma torus operating at more than 100moC and it will produce 500MW of fusion power, 10 times as much as the energy required to run the facility.

‘ITER is expected to prove definitively that fusion power is possible,’ Dendy said.’It is the last big experiment before we move on to a power station prototype. The project now has seven treaty partners – the EU, the US, Russia, China, Japan, South Korea and India – representing more than half the world’s population.

‘There is universal agreement that fusion is desirable and plausible, it’s now really a question of investments and timescales.’

The first plasma will likely not be generated at ITER until 2016 and Sir David King, the government’s chief science adviser, has said that as a commercial enterprise fusion power is still 35 years away.

However, it does have the potential ultimately to contribute to baseline power generation, claimed Dendy.

‘The power stations that run all the time, using coal and fission, could in theory be taken over by fusion, which has the added advantages of producing no carbon dioxide and no high-level nuclear waste.’

He added that there is going to be an increased national need for trained people in plasma physics.

‘This is where the new centre will be invaluable,’ he said.

‘The first plasma won’t be generated at ITER for at least a decade and the 35-year-olds who’ll be calling the shots in the control room will need to be starting their PhDs about now.

‘We don’t currently have a particularly strong university community in plasma physics and this has been recognised by the government. Now is the time to build on this.’

Crucial role

Plasma science will continue to play a crucial role alongside the engineering work to create a safe, effective method of harnessing fusion to generate electricity.

‘Our feeling is that fusion plasma physics raises a lot of interesting fundamental physics questions which we hope to pursue more deeply, such as in the area of turbulence,’ said Dendy.

‘But such fundamental questions are not always perceived as being on the direct path to designing a fusion reactor.

‘With the funding given to the new centre, we hope to have time to look more deeply and from a slightly more academic perspective at some of the interesting plasma physics questions that arise.’

Intellectual challenge

Dendy said that such topics will be investigated not only because they are interesting in themselves, but because they may have other applications elsewhere.

‘It’s important that the fusion programme feeds out into the wider plasma community but also because a deeper understanding is a good thing for the fusion programme as a whole.

‘Plasmas comprise most of the visible matter of the universe, and raise a whole range of fascinating intellectual challenges, whether in their natural state in space and astrophysics or whether in this extremely important energy application of fusion power,’ he concluded.

‘We should all welcome stronger engagement by UK universities in this area, in partnership with the world-leading facilities at Culham.’