New world record established for energy yield from nuclear fusion

It’s a week of breakthroughs and exciting announcements about nuclear fusion. Following exciting updates from US Inertial Fusion, scientists in the UK have announced the highest energy yield ever achieved from nuclear fusion.

A test in the Joint European Torus (JET) was able to generate a high fusion force for five seconds, releasing 69.26 megajoules of energy from just 0.21 milligrams of fuel. This corresponds to the energy you can get from 2 kilograms of coal. The fuel in question is a mixture of two types of heavy hydrogen, called deuterium and tritium, which will be used in the nuclear fusion power plants of the future.

Despite the record, JET is not designed to achieve the expected energy for these stations. It is a pioneer for large-scale prototypes such as ITER and DEMO. ITER will be launched next year and should generate ten times as much energy as it puts into it. Its successor, DEMO, will generate electricity and generate 25 times as much energy. Still, the JET results show the potential of this technology.

“Our successful demonstration of operational scenarios for future fusion engines such as ITER and DEMO, validated by the new energy record, inspires greater confidence in the development of fusion energy. In addition to setting a new record, we achieved things we have never done before and deepened our understanding of fusion physics,” said Professor Ambrogio Fasoli, program manager (CEO) at EUROfusion, in a statement.

“We can reliably create fusion plasmas using the same fuel mixture used by commercial fusion energy power plants, demonstrating the advanced expertise that has been developed over time,” said Dr. Fernanda Rimini, JET’s Senior Exploitation Manager.

JET, ITER and DEMO are a nuclear fusion design known as a tokamak. The melt plasma is confined in a doughnut-shaped chamber by powerful magnets. Fusion is the process that powers the sun and all the stars, but on Earth we don’t naturally have the pressures and temperatures that exist in the cores of these objects. So we have to be creative, and usually this means heating plasma to more than 100 million degrees.

At such temperatures, a lot of energy is released from the plasma (that’s the goal), but eruptions can occur that damage the confining walls. The fusion of deuterium and tritium creates helium and this byproduct must be disposed of without destroying the exhaust system. JET has shown that both challenges can be solved.

“Not only have we demonstrated how to mitigate the intense heat flowing from the plasma to the exhaust, we also showed in JET how to get the plasma edge into a stable state and thus prevent energy bursts from hitting the wall reaches. Both techniques are intended to protect the integrity of the walls of future machines. This is the first time we have ever been able to test these scenarios in a deuterium-tritium environment,” added Dr. Emmanuel Joffrin, leader of CEA’s EUROfusion Tokamak Exploitation Task Force, added.

A lot of energy is needed to create those high temperatures. In nuclear fusion, the goal is to achieve a Q factor higher than one, getting as much energy out as you put in. The only experiment to date that has achieved that was the inertial fusion system in the US, which had a Q of 1.5. The best JET has done is 0.69, but JET’s energy yield was 20 times higher than what inertial fusion achieved.

Commercial fusion power plants are still a few decades away, but these recent breakthroughs show that there are multiple paths to that goal and that only through further experimentation can we continue to refine and improve.

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