In the midst of an ever growing energy crisis, the search for reliable clean energy is at the forefront of modern physics. At the University of York, cutting edge research into nuclear fusion is developing the energy of the future.
Nuclear fusion is a means of generating energy that occurs when two atomic nuclei combine to form a heavier nucleus. It is the opposite of the better known nuclear fission, where a heavy atom is split to produce energy, the process used in nuclear power plants. Fusion is at the centre of powering the universe, being the process which powers the sun and other stars – in our sun, smaller atoms like hydrogen combine to form helium.
There has been a continuing effort in the past century to use fusion to produce electrical power on Earth. As an energy source it has the potential to be highly productive – it has the capacity to produce significant amounts of energy consistently without the emission of greenhouse gases in the same way as fossil fuels, or toxic waste in the same way as fission reactors. It is also inherently safe, given that if the reaction were to go wrong the fusion reactor would simply shut down, and can be operated constantly without being dependent on environmental factors. If fusion were to be successfully harnessed, it could potentially power the world.
However, actually producing fusion on Earth is a challenge for a host of reasons. For one, it requires massive amounts of heat to produce a reac-tion. As a result, the energy generally required to produce a fusion reaction is greater than the energy that can be collected. The goal of much of fusion research is therefore aimed at 'ignition' – the point where the output of a fusion reaction is greater than the input energy. This was achieved in principle at the National Ignition Facility in 2023, with the caveat that the system was not 100 percent efficient, meaning the actual energy used was much higher than the official input to the reaction.
Fusion reactors typically use deuterium and tritium, two isotopes of hydrogen that have particularly high reactivity at the temperatures that reactors can realistically reach. In a reactor, a plasma is confined, typically using either magnetic or inertial confinement. Magnetic confinement fusion (MCF) reactors are typically tokamaks, which are large devices that confine the plasma in a torus, a shape similar to a doughnut, using large magnets. Inertial confinement fusion (ICF) on the other hand uses high-power lasers on a small capsule of fuel.
A plasma, sometimes called the fourth state of matter, is an ionised gas that therefore has charged constituents and behaves differently to an ordinary gas – most of the visible universe is made of plasma, and it also has extensive technical uses besides fusion.
The York Plasma Institute at the University of York is at the forefront of fusion research and has one of the largest groups in Europe researching fusion, working on a range of fusion problems and collaborating with groups across the world. The group mainly focuses on magnetic confinement tusion (MCF), however it has a range of research that also covers inertial confinement fusion (ICF), as well as low temperature plasmas and technology. The group has involvement in several international fusion projects, including ITER in France, which is currently being constructed as the largest tokamak in the world, as well as the National Ignition Facility in California, which operates 192 lasers to produce ICF.
The York Plasma Institute is also heavily involved in the Spherical Tokamak for Energy Production (STEP), the UK's project to build a tokamak in West Burton in Nottinghamshire by 2040. The project is part of heavy investment into developing fusion energy from the UK Atomic Energy Authority, with the government having pledged hundreds of millions of pounds towards the project.
Fusion is certainly the energy of the future, although the path ahead is a long one. The struggle towards fusion energy is a massive international effort, including work from specialists across the world, as well as huge amounts of investment from governments and private companies, but we are not going to be using fusion power for quite some time. The fusion devices being constructed now are still only prototypical, and they themselves are years away from completion, and there is still a host of physics, engineering and socioeconomic problems that need to be solved. We are just seeing the beginning of the funding, construction and manpower that is going to be needed to develop fusion energy to its full potential, but given time and investment, it could be the energy of the future
Nouse spoke to Dr Istvan Cziegler, lecturer and researcher at the York Plasma Institute, whose research investigates plasma turbulence in tokamaks. Speaking on fusion energy, Dr Cziegler said "people who work on fusion don't have this illusion that what we are working on is solving the climate problem right this second."
"It's not for today or tomorrow, the whole idea of working on fusion is for prosperity".
