Nuclear fusion – replicating the power of the sun

Nuclear fusion is the source of power for the Sun and other stars, releasing vast amounts of energy in the forms of light and heat.

For a long time, nuclear fusion has been a promising new source of energy here on Earth. The ongoing joke about nuclear fusion though is that it is 30 years away and always will be. Yet over the last couple of years there have been signs that this may change

Nuclear fusion is a process in which two or more atomic nuclei (reactants), usually deuterium and tritium, combine to form products. The difference in mass between the reactants and products results in the release of energy.

Branches of nuclear fusion

There are two main branches of fusion research, those that use magnetic confinement, typically doughnut shaped tokamaks, to confine the fuel and those that use inertial confinement with lasers.

In April 2024 First Light Fusion, a company in the UK, made a significant breakthrough using a novel fusion method. In this method a target containing fusion fuel is compressed, using a projectile travelling at high speed. First Light Fusion has plans for a new, larger base in Culham - which had previously been home to the Joint European Torus (JET) tokamak facility. In JET’s final experiment at the end of 2023, after 40 years of being in operation, it produced a record 69 megajoules of energy over five seconds.  

Also, in April 2024 the Korea Superconducting Tokamak Advanced Research (KSTAR) experimental reactor ran at 100 million °C (180 million °F) for 48 seconds which at this time is a world record. China’s Experimental Advanced Superconducting Tokamak (EAST) has run for longer than this but at a lower temperature.

On the inertial confinement side, the National Ignition Facility (NIF) in the US achieved ignition multiple times at the end of 2023. Ignition being a fusion reaction that produces more energy than is injected into it. The NIF fires 192 laser beams at a frozen pellet of hydrogen isotopes that sits in a diamond capsule suspended inside a gold cylinder to achieve fusion.   

The future of nuclear fusion

In the future the International Thermonuclear Experimental Reactor (ITER) is currently being built in France whilst there are already plans in place for its successor called DEMOnstration power plant (DEMO) which would be the first commercial fusion power plant that was able to supply power as a normal power plant does.

There is so much research into nuclear fusion because it is a promising source of energy for several reasons:

• Abundant fuel: the typical fuel source are isotopes of hydrogen, deuterium and tritium, which are abundant and can be extracted from water and lithium, respectively. 
• High energy density: fusion reactions release a tremendous amount of energy compared to the mass of fuel consumed.
• Low radioactivity: fusion reactions produce very little long-lived radioactive waste compared to nuclear fission reactions. Tritiated water is the main radioactive byproduct of fusion which has a relatively short half-life.
• Safety: fusion reactors have inherently safe designs and do not carry the risk of catastrophic accidents or meltdown as fusion reactions do not produce runaway chain reactions like nuclear fission reactions.
• Minimal environmental impact: fusion reactions do not emit greenhouse gases or produce air pollution.
• Energy security: fusion energy could provide a reliable and sustainable source of energy, reducing dependence on fossil fuels and enhancing energy security.
• Global cooperation: fusion research and development have historically been international efforts, fostering collaboration among nations and promoting peaceful cooperation in the pursuit of clean energy solutions.

Nuclear fusion and Inspec

Inspec covers all aspects of Nuclear Fusion research.

In section A (physics), the following subject classifications contain relevant information:

• A2852: Fusion reactors
• A2852C: Fusion reaction ignition
• A2852F: Fusion reactor materials
• A2852J: Fusion reactor theory and design
• A2852L: Fusion reactor instrumentation
• A2852N: Fusion reactor safety
• A5250J: Plasma production and heating by laser beams
• A5255G: Plasma in torus (stellarator, tokamak, etc.)
• A5255M: Nonmagnetic plasma confinement systems (e.g. electrostatic, inertial, high frequency and laser confinement, etc.)
• A5255P: Confinement in fusion experiments
• A5275: Plasma devices and applications

Relevant controlled terms from the Inspec Thesaurus include:

• fusion reactor blankets
• fusion reactor design
• fusion reactor divertors
• fusion reactor fuel
• fusion reactor ignition
• fusion reactor instrumentation
• fusion reactor limiters
• fusion reactor materials
• fusion reactor operation
• fusion reactor reaction chamber
• fusion reactor safety
• fusion reactor targets
• fusion reactor theory
• fusion reactors
• laser fusion
• nuclear fusion
• plasma inertial confinement
• plasma production by laser
• plasma toroidal confinement
• Tokamak devices