Replicating fusion, the power source of the stars, here on Earth has been a great challenge ever since the first experiments took place in the 1950s. Today, scientists and engineers continue to make new discoveries, bringing this virtually limitless energy source closer to the present. Over the years, a variety of experimental fusion devices have been designed and constructed, including tokamaks, stellarators and laser-based technology, to advance the promise of fusion energy and one day drastically transform the way we generate energy.
There are currently over 130 experimental public and private fusion devices operating, in construction or planned around the world, based on different approaches to producing fusion reactions and having a variety of designs. To review this multitude of devices, the IAEA has published a new report World Survey of Fusion Devices 2022, which further elaborates the information available on the IAEA's online database called Fusion Device Information System (FusDIS).
"When it is realized, fusion would benefit every country and work alongside nuclear energy and other forms of sustainable energy, supporting climate change mitigation and contributing to the energy mix," said Matteo Barbarino, an IAEA Nuclear Plasma Fusion Specialist. "Fusion could benefit virtually every country and that is one of the reasons why it is so important."
"All over the world, researchers and engineers are exploring different fusion device designs to move progress forward," he continued. "And our new publication provides a comprehensive overview of fusion research and development activities from the perspective of those devices capabilities."
Nuclear fusion is a process in which atomic nuclei combine to form a heavier nucleus, releasing a large amount of energy. However, achieving sustained and controlled fusion reactions in a practical setting is associated with a number of scientific and technical challenges. To keep such a reaction going, the fuel - usually isotopes of hydrogen - must be confined and maintained at intense pressures and extremely high temperatures several times hotter than the core of the Sun.
Considerable progress continues to be made. More than 30 countries have carried out experiments with different types of fusion devices, often successfully achieving fusion reactions, although for short periods and without generating yet useful amounts of energy.
All over the world, researchers and engineers are exploring different fusion device designs to move progress forward and our new publication provides a comprehensive overview of fusion research and development activities from the perspective of those devices capabilities.
Different approaches, same goal
The new report dedicates each chapter to a different design class, providing details including its name, status, ownership, host country and organization with short descriptions of the device's goals and main features. It also provides statistics about publications, funding and other parameters that help create a comprehensive picture of the status of global fusion efforts.
Tokamaks and stellarators, for example, are the most common devices and the focus of much of the current research. These toroidal devices contain large magnets that control the movement of plasma - a high temperature, charged gas - where fusion occurs. The report shows that there are currently more than 50 tokamaks and over 10 stellarators in operation in the world. The world's largest tokamak, ITER, is currently under construction in France, with 35 countries involved in the project.
Another approach includes inertial fusion, which uses high-power lasers (or other means) to heat and compress tiny spherical capsules containing fuel pellets. In December last year, using this approach the National Ignition Facility (NIF) in the United States made significant progress in fusion research, generating about 3.15 megajoules (MJ) of energy from the 2.05 MJ energy output of its 192 lasers. " This year we find ourselves in a position where we can talk about the milestones of burning plasmas, fusion ignition, and target energy gain greater than unity in the past tense - a situation that is remarkable," said Omar Hurricane, Chief Scientist for the Inertial Confinement Fusion Program Design Physics Division, Lawrence Livermore National Laboratory, USA.
The report also details the alternative designs scientists continue to work on for producing fusion, for example, colliding two ion beams generated by particle accelerators with each other, with fusion taking place at their collision point, or trying out fuels other than hydrogen isotopes, such as those based on fusing a proton with boron-11.
To demonstrate that fusion can effectively produce electricity, there is an increasing effort towards design and construction of demonstration fusion power plants, or DEMOs, which today also include investments being made by the private sector. The report also dedicates a chapter to the 12 DEMO concepts at various stages of development in China, Europe, Japan, Russia, the Republic of Korea, the United Kingdom and the United States of America, with varying target completion dates spanning the next three decades. "We've made significant progress in understanding fusion and its science, but there is still much work to do before it can become a practical source of electricity," said Barbarino.
