Laser fusion a step closer

Scientists are one step closer to fusion power thanks to work at the Rutherford Appleton Laboratory that heated significant volumes of solid matter to temperatures of 10 million degrees Kelvin

View of the Vulcan petawatt target chamber with Mr Dan Hey (University of California Davis, top right). Credit: STFC

The international team of physicists from Japan, the EU and the US used intense laser pulses – producing is 100 times the entire world’s electricity production - from the Vulcan petawatt laser facility at the STFC Rutherford Appleton Laboratory in Oxfordshire.

A reasonable volume of matter is needed to initiate the fusion process to enable energy gain (to get more energy out than the energy needed to produce it). Previously only ultra-thin layers of matter had been heated to similar temperatures.

This new work confirms that the heated material stays at this temperature and at solid density for a least 20 picoseconds – which is more than enough time for high speed instruments, such as X-ray spectrometers, to probe the heated material. “This is an exciting development – we now have a new tool with which to study really hot, dense matter. Careful selection of the target parameters allows access to this new regime,” said Professor Peter Norreys from STFC Rutherford Appleton Laboratory and Imperial College London – the Principal Investigator of the experiments.

The Vulcan petawatt laser facility provides staggeringly powerful pulses of energy to target. One petawatt (1015 Watts) is 100 times the entire world’s electricity production and the laser beam is focused to a spot of a few microns across – about one tenth the size of a human hair. It only lasts for less than 1 picosecond (10-12 of a second) but during that time, it is possible to heat materials above their normal melting point - allowing conditions that are found in exotic astrophysical objects such as supernova explosions, white dwarfs and neutron star atmospheres, to be created.

The UK has proposed an even more powerful laser facility, known as Hiper (High Power laser Energy Research), which will study the feasibility of laser fusion as a potential future energy source.

“Hiper is a proposed, very large-scale facility and so we have to check that our understanding is correct,” said Professor Norreys.

The work is published in the New Journal of Physics.