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FEATURE LASER FUSION A STAR IN A BOX


The nuclear fusion reactions desired in facilities like the National Ignition Facility (USA), Dipole (UK) and Laser Mégajoule (France) aim to recreate the reactions that keep stars burning. Keeping a star in a box requires some engineering prowess. The NIF boasts: lA 30 x 30m concrete silo target bay with two-metre-thick walls and doors;


lA 10m diameter target chamber made of 10cm thick aluminium and 30cm thick concrete walls, with holes for the diagnostic equipment and 192 beams;


lA metre-thick region of lithium to absorb energy to heat water to create steam for the turbine. It also produces tritium, when struck by the high energy neutrons, which can be used as fuel; and


l7m-long positioning arms to hold the target in place.


Before each experiment, a positioner precisely centres the target inside the target chamber and serves as a reference to align the laser beams


community and in industry, with companies like Gooch and Housego, a very strong position in the world; the UK is world leading in several of these areas.’ He continued: ‘There is a challenge in the UK for the government to decide if laser fusion is going to be a large contributor to energy supply in the second half of the century, and if so the UK should clearly be involved it that.’ In order to further laser fusion, government


A metallic case called a hohlraum holds the fuel capsule for NIF experiments. Target handling systems precisely position the target and freeze it to cryogenic temperatures (18 kelvins, or -427 degrees Fahrenheit) so that a fusion reaction is more easily achieved





to devise the best way to harness the power from these reactions and to turn it into a commercial product while also figuring out how to ensure that the process is safe. They are also trying to find companies that could manufacture the parts required to make the fusion plants.


A pane in the glass The equipment used for these proof-of-concept projects is often specialised and unique for the application. Smith gave an example of the glass that was manufactured for NIF: two factories were built to make it – and the glass, if stacked, would be about a foot wide and 1.5 miles long. These large projects, such as NIF, often involve


government funded research programmes, which turn to industry to build the components. According to Jones, the relationship between research and industry is especially strong in the UK: ‘Today, the UK has both in the research


24 ELECTRO OPTICS l FEBRUARY 2014


interest needs to be kept high in order to capitalise on the eventual success of either NIF or LMJ. Jones stated: ‘Maintaining an adequate level of industrial and academic capability is going to be critical because if the UK does that and takes it forward it would be a major contributor to wealth creation in the UK.’ But with current austerity


measures and reduced government funding, the UK could lose impetus in laser fusion research. This could mean that the UK becomes reliant on other nations instead of providing components and expertise to them. Jones has concerns over the future of ICF and the UK. ‘If the UK lets its lead go and doesn’t continue to invest in research and industry in the intervening years it could be that when, finally, laser fusion does make it into the energy supply and becomes a multi-billion dollar industry, the risk is that the UK won’t benefit from the leadership it has today.’


Over the anticipated timeframe for ICF to be


ready for commercial use, maintaining this level of interest and technological knowhow could prove difficult and, yet, it is essential. Jones explained: ‘It’s on a [financial] scale, and on a time scale, that is not consistent with investment from small companies such as Gooch and Housego, you’re


talking about investing for returns that are waiting for decades to come. Similarly, the plants that you would need to produce the parts for these very big laser systems are large and expensive. You can’t take this sort of proposition to your shareholders and say “we would like you to invest in this; it will be great in 10 or 20 years time”. They would laugh at you.’


Industry is not going to jump in and take a 20-year risk all by itself – which is why the government needs to help


This is where the UK government comes in, it needs to recognise and stick with ICF as a technology of the future for the sake of, what Jones refers to as ‘UK PLC’. He reaffirmed: ‘If it is not regarded as a priority, the UK could lose its lead which would mean that if ICF takes off as a leading technology, the UK would be a customer and not a supplier.’


Jones uses the model that was instigated in the US to


show how the government could keep industry interested: ‘The use of industry that took place in the US shows that it can be involved and benefit from doing the “big science”. So they have not just created a great scientific research facility, they have also created an industrial capability along the way.’ This is something that Jones thinks the UK should be trying to do as well: ‘There is no use in generating this research base without the industrial capabilities that go with it.’ He concluded: ‘It’s going to be critical that if the next generation of systems are developed there needs to be a way to ensure that the UK industry will benefit,’ adding that industry is not going to jump in and take a 20-year risk all by itself – which is why the government needs to help. However, both Jones and Smith feel that this is unlikely to happen until facilities like NIF have proven that ICF can successfully break even in terms of energy. l


@electrooptics | www.electrooptics.com


Lawrence Livermore National Laboratory


Lawrence Livermore National Laboratory


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