Since the 1950s, scientists have tried to ensure that nuclear fusion generates more energy than it consumes when producing it, and in December 2022 researchers from the Lawrence Livermore National Laboratory (California) reached a historic achievement. For the first time, they obtained more energy than the fuel absorbed to create it: 3 megajoules of energy using only two, which implies a 50% energy gain.

In nuclear fusion, energy is released when the nuclei of atoms combine or fuse with each other to form a larger nucleus. This is how the Sun produces energy. In nuclear fission, however, which is what nuclear power plants use, nuclei separate to form smaller nuclei, thus releasing energy.

Fusion reactions, unlike fission reactions, do not produce carbon or long-lived radioactive waste, and can become a practically inexhaustible source of electricity production, since their fuel is two isotopes of hydrogen (deuterium and tritium), which are very abundant in nature due to the large proportion of water on the earth’s surface. They are all advantages and the only problem to solve is how to obtain net energy gain from nuclear fusion.

New step towards fusion

In this process towards reaching the holy grail in energy production, another relevant event has now occurred: the fusion reactor. Joint European Torus (JET) of Great Britain just set an energy record in its latest experiment.

It obtained 69 megajoules of energy from just 0.2 milligrams of deuterium-tritium fuel. That means it achieved more energy than any other previous fusion experiment: this record is equivalent to the energy released by burning 2 kilograms of coal, the researchers explain.

However, it had to use more energy to heat the plasma than was produced by nuclear fusion, so it had no net energy gain, as Lawrence Livermore National Laboratory had done.

However, the JET record is 20 times the amount of energy released at Lawrence Livermore National Laboratory, which used a different approach to fusion to produce more energy than was absorbed by the fuel. The JET team’s new achievement surpasses its previous world records of 59 megajoules (2022) and 22.7 megajoules (1997).

JET scientists were able to reliably reproduce the fusion conditions necessary for the new record in multiple experimental pulses, demonstrating the understanding and control they have achieved over the complex fusion processes, the researchers explain.

Objective: ITER

The highlight of this achievement is that it provides important information for the future large-scale European reactor ITER (Thermonuclear Experimental Reactor), the largest and most advanced fusion experiment in the world, founded in 2007 and with the collaboration of 35 countries ( among them Spain).

ITER, still under construction, has among its objectives to achieve nuclear fusion with a net gain of energy, as well as to maintain fusion for long periods of time, objectives that the new experiment contributes to achieving.

“Perhaps even more interesting to me than the record is what we have achieved in terms of operational scenarios for ITER,” Explain the head of the EUROfusion Tokamak Exploitation Working Group, Emmanuel Joffrinfrom CEA, French member of EUROfusion.

“We not only demonstrated how to smooth out the intense heat flowing from the plasma into the exhaust, but we also showed in JET how we can get the edge of the plasma to reach a stable state, thus preventing energy bursts from reaching the wall. Both techniques aim to protect the integrity of the walls of future machines. This is the first time we have been able to test those scenarios in a deuterium-tritium environment,” he adds.

Greater confidence

Specific updates made over the last decade have brought the JET’s technical specifications as close as possible to those of ITER, allowing for studies that will allow that future machine to begin operating when it comes into operation.

Dr. Fernanda RiminiJET’s scientific operations leader, says: “We can reliably create fusion plasmas using the same fuel mixture that commercial fusion energy power plants will use, demonstrating the advanced expertise developed over time.”

The protagonists of this achievement consider that it instills greater confidence in the development of fusion energy. “Beyond setting a record, we achieved things we had never done before and thus deepened our understanding of the physics of fusion,” says the professor. Ambrogio Fasoliprogram director (CEO) of EUROfusion.

JET has been the world’s largest and most successful fusion experiment, and a central research facility of the European Fusion Programme. The machine is based at the UKAEA campus in Culham, UK, and has been a collective facility used by European fusion researchers under the direction of the consortium. EUROfusion.