Inertial Fusion Energy: Optimising High Energy Density Physics in Complex Geometries

Climate change driven by burning coal or oil, and fuel supply insecurity caused by international conflicts highlight the need to develop safer, cleaner ways of generating electrical power. Renewables and nuclear fission both play an important role here, but each has limitations. Wind and waves are subject to natural variations, while fission reactors require careful, long term management of dangerous waste.

One attractive alternative for the future is fusion energy, harnessing the same nuclear reactions that power the sun. To create fusion on Earth we "burn" an isotope of hydrogen (deuterium, 0.03% of the mass in the world's oceans), a vast, easy to access fuel supply. The deuterium is combined with tritium (another hydrogen isotope) and under extremes of temperature, pressure and density these can fuse to form Helium and in doing so release huge amounts of energy. The reaction generates no greenhouse gasses, and is relatively clean with very short lived, easy-to-handle waste material, however the conditions required to create fusion are very difficult to make.

There are several methods for getting to Fusion conditions, including using large magnets to trap a hot plasma over long timescales, or utilising an array of lasers to suddenly heat and compress a small pellet of frozen fusion fuel, causing it to implode in a spherically symmetric fashion. This last method, called Inertial Confinement Fusion, recently had a breakthrough in results, with the world's most complex, expensive laser, being utilised to heat a precisely engineered fusion target to the point of causing 'ignition' where heat generated within the target was briefly enough to sustain the continued burn of fusion fuel. However, with present laser technology it would be challenging to scale such a method to energy production.

In new experiments at First Light Fusion, a company based in Oxfordshire, a different approach to fusion is being developed. Instead of lasers hitting the fuel capsule from all sides, a single high speed projectile is used to hit a specially machined metal and plastic target from just one side. Inside the target, shockwaves from the impact of the projectile are shaped and concentrated, compressing and heating an enclosed volume of Deuterium-Tritium fuel. In April 2022 First Light Fusion released their first results, demonstrating that this method provides a promising route that warrants further research.

Our project brings together three universities, Imperial College, Oxford and York in partnership with First Light Fusion and a new company dedicated to AI techniques - Machine Discovery - to form a Partnership that will explore the challenges in the First Light Fusion approach. Working together we will study the flow of heat, matter and radiation in First Light Fusion's targets which have complex interfaces between vastly different material pressures, from over a billion atmospheres to room pressure, and material temperatures, from millions of 0C to those lower than liquid nitrogen.

By exploring these exciting conditions and learning how heat, radiation and matter flow in the targets, we hope to be able to better simulate how these targets behave. This will enable First Light Fusion to design much higher yield experiments that could lead the way to 'on grid' power production. The high yield experiments will require projectiles moving at many 10s of km/s which will be achieved by using huge bursts of electrical current - 50 million amperes! - and the magnetic fields this creates to launch large strips of metal to these ultra-high velocities. The £500million generator to make such high currents is presently being designed and will be built in the UK, helping our nation maintain its position as a world leader in fusion technology and industry.