Are We a Step Closer to Nuclear Fusion?
We may be a step closer to realising the dream of using nuclear fusion to create limitless supplies of energy. An international team claims to have created a technique where they can ‘see’ where energy is delivered during fusion. 
Seeing the energy flow could allow scientists to test different ways to improve a fusion reactor’s design, they claim.
The team, led by the University of California, San Diego and General Atomics, used the technique a nuclear fusion profession known as ‘fast ignition’. Fast ignition involves two main stages to start nuclear fusion.
First, hundreds of lasers compress the fusion fuel – typically a mix of deuterium and tritium – which are contained in a spherical plastic fuel capsule. Then, a high-intensity laser delivers energy to rapidly heat and ignite the compressed fuel.
Scientists consider fast ignition a promising approach toward controlled nuclear fusion because it requires less energy than other designs.
But in order for fast ignition to work as it should, researchers need to overcome a big hurdle; how to direct energy from the high-intensity laser into the densest region of the fuel.
‘This has been a major research challenge since the idea of fast ignition was proposed,’ said Farhat Beg, professor of mechanical and aerospace engineering at UC San Diego.
To tackle this problem, the team devised a way to see, for the first time, where energy travels when the high-intensity laser hits the fuel target.
The technique relies on the use of copper tracers inside the fuel capsule.
When the high-intensity laser beam is directed at the compressed fuel target, it generates high-energy electrons that hit the copper tracers and cause them to emit X-rays that scientists can image.
‘Before we developed this technique, it was as if we were looking in the dark,’ said Christopher McGuffey, assistant project scientist.
‘Now, we can better understand where energy is being deposited so we can investigate new experimental designs to improve delivery of energy to the fuel.’
The breakthrough follows news last month that scientists were able to successfully switch on the world’s largest ‘Stellarator’ fusion reactor. Dubbed Wendelstein 7-X (W7-X), the reactor is designed to contain super-hot plasma for more than 30 minutes at a time.
After experimenting with different fuel target designs and laser set ups, researchers eventually achieved a record high efficiency of energy delivery.
‘We hope this work opens the door to future attempts to improve fast ignition,’ said Beg.
The breakthrough follows news last month that scientists were able to successfully switch on the world’s largest ‘Stellarator’ fusion reactor.
Dubbed Wendelstein 7-X (W7-X), the reactor is designed to contain super-hot plasma for more than 30 minutes at a time.
Last month, the reactor produced a special super-hot gas for a tenth of a second. Scientists hope that, if it can work for longer, it could eventually lead to limitless supplies of clean and cheap energy.
Read more at www.dailymail.co.uk
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