Ignition is a key process that amplifies the energy output from nuclear fusion and could provide clean energy and answer some huge physics questions.

A new experiment appears to have triggered ignition for the first time, at the National Ignition Facility (NIF) at Lawrence Livermore Laboratory in the US, recreating the extreme temperatures and pressures found at the heart of the Sun.

Controlled fusion in the laboratory is one of the defining scientific grand challenges of this era and this is a momentous step forward.
Professor Jeremy Chittenden

This has produced more energy than any previous inertial confinement fusion experiment, and proves ignition is possible, paving the way for reactions that produce more energy than they need to get started.

Imperial College London physicists are already helping to analyse the data from the successful experiment, which was conducted on 8 August 2021. Imperial has also produced more than 30 PhD students that have gone on to work at the NIF. The College retains strong links with the facility, and others throughout the world, through the Centre for Inertial Fusion Studies (CIFS).

Momentous step forward

Co-director of the Centre for Inertial Fusion Studies at Imperial, Professor Jeremy Chittenden, said: “Demonstration of ignition has been a major scientific grand challenge since the idea was first published almost 50 years ago. It was the principal reason for the construction of NIF and has been its primary objective for over a decade.

“After ten years of steady progress towards demonstrating ignition, the results of experiments over the last year have been more spectacular, as small improvements in the fusion energy output are strongly amplified by the ignition process. The pace of improvement in energy output has been rapid, suggesting we may soon reach more energy milestones, such as exceeding the energy input from the lasers used to kick-start the process.

“This is crucial for opening up the promise of fusion energy and allowing physicists to probe the conditions in some of the most extreme states in the Universe, including those just minutes after the Big Bang. Controlled fusion in the laboratory is one of the defining scientific grand challenges of this era and this is a momentous step forward.”

Co-director of the Centre for Inertial Fusion Studies at Imperial, Professor Steven Rose, said: “The NIF team have done an extraordinary job. This is the most significant advance in inertial fusion since its beginning in 1972.

“What has been achieved has completely altered the fusion landscape and we can now look forward to using ignited plasmas for both scientific discovery and energy production.

Reaching ignition

The type of nuclear reaction that fuels current power stations is fission – the splitting of atoms to release energy. Fusion instead forces atoms of hydrogen together to gain energy, producing a large amount of energy, and, crucially, limited radioactive waste.

For this reason, a way to create efficient fusion reactions has been sought for decades to produce clean energy using few resources. However, fusion reactions have proven difficult to control and to date, no fusion experiment has produced more energy than has been put in to get the reaction going.

While the latest experiment still required more energy in than it got out, it is the first to reach the crucial stage of ‘ignition’, which allowed considerably more energy to be produced than ever before, and paves the way for ‘break even’, where the energy in is matched by the energy out.

Original Article: Major nuclear fusion milestone reached as ‘ignition’ triggered in a lab

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