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What is fusion?

Here, we will find out about the process of fusion, why we are working towards it, and what this ‘star in a jar’ might look like.
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The sun brings energy and life to the world. Could it be a model for our future? Could we build our own sun here on earth? Scientists are trying to do just that –
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but why? The sun brings energy to the planet, and we all need energy in our lives. At the moment we have several ways of producing energy, but they aren’t all sustainable. Fossil fuels like oil, coal and gas will one day run out. They also damage and pollute the environment. We have clean and renewable ways of producing energy, like wind and solar power, but they won’t be able to provide enough energy for everyone in the future. And they depend on the wind blowing and the sun shining. When it’s a beautiful bright day outside, it seems obvious that the sun is producing a lot of energy, but where does that energy come from? The secret is hidden in its core.
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What is that secret?
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The sun is driven by a process called nuclear fusion, which releases vast amounts of energy.
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Scientists built miniature suns here on earth to try and make fusion happen inside them. We can look inside the mini-suns using cameras. This is a video of what happens inside a mini-sun called MAST here in the UK. At the University of York we video-conference with scientists working on the mini-suns at Culham in Oxfordshire, and help run experiments on them. We analyze experimental and simulation data to see how well the mini-suns are working and how we can improve them. If we could make energy the way the sun does, we could change the planet when we need it most. Fossil fuels like oil are running out and we use large amounts of them.
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But if we used our mini-suns, we would only need small quantities of water to release huge amounts of energy.
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But our miniature suns don’t yet work perfectly. Sometimes they burn out. One of the problems is that we don’t yet have materials that can contain a really hot mini-sun. This video shows MAST flickering and then dying out. This melts the walls of our many suns and we have to replace them Scientists in the Fusion Doctoral Training Network, which includes the University of York, are working on ways of stopping the suns flickering so much, which would then protect the walls. We are also trying to find better materials to build them. In France, scientists are building the biggest mini-sun ever called ITER. This simulation shows what ITER will look like when it’s built.
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It’s so big that we need robots to help build it. Ongoing work like this brings us ever closer to one day building a mini-sun on earth. We hope that in the future, our mini-suns will join other clean sources of energy to power our cities, reduce pollution and keep our lives running day and night.

All stars, including our Sun, are made of plasma. Stars generate enormous amounts of power through a process called fusion. Harnessing this power here on Earth would give us a near limitless supply of low-carbon energy.

Here, we will find out about the process of fusion, why we are working towards it, and what this ‘star in a jar’ might look like.

Why fusion?

The process of fusion creates no carbon dioxide. This means that the reaction does not contribute to climate change.

The fuel needed for fusion (hydrogen) is also readily available or easily made here on Earth. This means that fusion has the potential to provide a near limitless supply of energy.  One of the so-called isotopes of hydrogen is called deuterium and makes up about one in every 6,000 atoms of hydrogen found in seawater. The second is another form of hydrogen, known as tritium. This is radioactive, so not found abundantly in nature. However, we can make it in the fusion power plant by breaking down lithium nuclei. A single bath of seawater and the lithium from two laptop batteries provides enough deuterium and tritium to provide the average lifetime power needs for one person living here in the UK.

As it is a nuclear process, fusion does create some radioactive waste. However, this waste decays very rapidly and does not remain radioactive, so there is no need to find long-term storage solutions. There is also no ‘chain reaction’ in fusion – in fact, the difficulty is keeping it going, not making it stop! This means there is no risk of a meltdown and this is a technology that can be safely shared with the world.

What do you already know about fusion? Had you heard of it before?

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Frontier Physics, Future Technologies

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