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.

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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 could allow scientists to test different ways to improve a reactor's design

HOW DOES FUSION POWER WORK? Fusion involves placing hydrogen atoms under high heat and pressure until they fuse into helium atoms. When deuterium and tritium nuclei - which can be found in hydrogen - fuse, they form a helium nucleus, a neutron and a lot of energy. This is down by heating the fuel to temperatures in excess of 150 million°C, forming a hot plasma. Strong magnetic fields are used to keep the plasma away from the walls so that it doesn't cool down and lost it energy potential. These are produced by superconducting coils surrounding the vessel, and by an electrical current driven through the plasma. For energy production. plasma has to be confined for a sufficiently long period for fusion to occur. Advertisement

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

ZERO-EMISSION FUSION REACTOR CLAIMS TO BE CHEAPER THAN COAL A fuel with no greenhouse emissions or radioactive waste that is almost unlimited, sounds too good to be true. But scientists have taken one more step to make fusion power useful and affordable. Engineers have designed a concept for a fusion reactor which, when scaled up to the size of a large electrical power plant, would rival costs for a new coal-fired plant with similar electrical output. Fusion, the process that powers the sun and other stars, entails forging the nuclei of atoms to release energy, as opposed to splitting them, which is fission - the principle behind the atomic bomb and nuclear power. Engineers from the University of Washington have published their design and analysis findings and will present them at the International Atomic Energy Agency's Fusion Energy Conference in St. Petersburg, Russia, earlie this year. The design builds on existing technology and creates a magnetic field within a closed space to hold plasma in place long enough for fusion to occur - allowing the hot plasma to react and burn. The reactor itself would be largely self-sustaining, meaning it would continuously heat the plasma to maintain thermonuclear conditions. Heat generated from the reactor would heat up a coolant that is used to spin a turbine and generate electricity, similar to how a typical power reactor works. 'Right now, this design has the greatest potential of producing economical fusion power of any current concept,' said Thomas Jarboe, a professor of aeronautics and astronautics at the university. Advertisement

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.