The European Union Ring JET achieves a new record for controlled nuclear fusion energy

Nuclear fusion has long been considered an ideal future green energy source, and stars like the Sun are powered by nuclear fusion, so it is also known as the "artificial sun". The main process of nuclear fusion is the fusion of the isotopes of hydrogen at high temperatures— deuterium and tritium — to form helium, a process that releases enormous amounts of energy in the form of heat. In addition, fusion can achieve nearly unlimited clean electricity energy over a long period of time with only a small amount of fuel obtained from cheap materials on a global scale; more importantly, nuclear fusion is inherently safe because it does not cause "out of control" chain reactions.

For this ideal future energy source, there have been recent new developments. On 9 February 2022, the European Fusion R&D Innovation Consortium (EUROfusion), the UK Atomic Energy Authority (UKAEA) and the International Thermonuclear Experimental Reactor Programme (ITER) jointly announced that on 21 December 2021, a research team from Europe achieved a new record for controlled nuclear fusion energy: they are in the world's largest fusion reactor, the European Union Ring (JET), Hydrogen's isotopes, deuterium and tritium, were heated to 150 million degrees Celsius and held steady for 5 seconds, while a nuclear fusion reaction occurred, and the nuclei fused together, releasing 59 megajoules (MJ) of energy.

Figure | European Joint Ring (JET) (Source: UK Atomic Energy Authority)

The controlled nuclear fusion energy value of 59 MJ broke the record of 22 MJ also set by JET 25 years ago, and is more than 2.5 times the previous record. It is roughly equivalent to twice the kinetic energy of a fully loaded truck traveling at 160 kilometers per hour.

Steven Cowley, director of the Princeton Plasma Physics Laboratory (PPPL), later commented, "It's fantastic to see a lens that stays high in 5 seconds. ”

JET, which has achieved a new record for controlled nuclear fusion energy, is currently the only device in the world that can operate using a mixture of deuterium and tritium, located at the UK Atomic Energy Authority base in Culham, Oxfordshire, UK. Designed and built by members of the European fusion programme EUROfusion, it has been in operation since 1983 and is technically operated by the Callum Fusion Energy Centre in Oxford, UK, where technicians from eurOfusion laboratories regularly work at JET.

Although JET's success this time does not mean that fusion power generation will soon flow into the grid – it will have to reach about 3 times the energy of this fusion reaction. But this achievement is very exciting news for its next-generation ITER project. Alberto Loarte, head of iter's science division, says, "It strongly confirms our strategy at ITER."

Jet and ITER, two fusion devices, use similar principles and methods – both are Tokamak devices: ring-shaped containers wrapped in a powerful magnetic grid in which magnets hold superheated ionized gases or plasmas in place and prevent them from touching and melting the vessel walls.

The slow pace of nuclear fusion studies on JET led researchers to design the larger and more advanced ITER in the 1990s, a giant 20-meter-wide tokamak device that could hold 10 times more plasma than JET. According to the simulation, the larger the volume of the plasma, the more difficult it is for heat to escape, allowing nuclear fusion conditions to remain for longer.

Located in the south of France, the ITER plant is co-funded by seven members– China, the European Union, India, Japan, South Korea, Russia and the United States – at a total cost of about $25 billion and is scheduled to start operating in 2025, but by 2035, when a large amount of electricity is generated, it will take until 2035. The seven parties involved in the project cover the world's major nuclear powers and major Asian countries, which have a population of nearly half the world's total. China's participation in the ITER program is also based on long-term energy basic needs.

The reason why the achievements of jet experiments confirm ITER's strategy is mainly because IN THIS EXPERIMENT, JET replaced the carbon lining of the plasma container with the same mixture of beryllium and tungsten metal as ITER.

In fact, the early operation of JET taught ITER designers an important lesson. Carbon was used in the lining of jet's plasma vessels before because it resists melting. But it turned out that these carbon linings would "absorb fuel like a sponge." Therefore, the lining material was replaced by beryllium metal and tungsten when designing ITER. Not only is tungsten metal more corrosion resistant than carbon, but it can also store more hydrogen.

In this experiment, in order to make the experimental conditions of JET as close as possible to future ITER, the researchers replaced the plasma container lining with a mixture of beryllium and tungsten. The experiment also confirmed the researchers' design: even at temperatures ten times higher than the center of the sun, a record level of nuclear fusion energy was achieved.

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