A faster and less expensive path to melting energy

Scientists are working to dramatically accelerate the development of fusion energy to power the electricity grid early enough to help mitigate the effects of climate change. The advent of breakthrough technology – high-temperature superconductors, which can be used to build magnets producing stronger magnetic fields than before – could help them achieve this goal. The researchers plan to use this technology to make magnets at the scale required for fusion, and then build what would be the world's first fusion experiment to generate net energy gain.

It is a collaboration between the Plasma Science & Fusion Center and the Commonwealth fusion systems of the Massachusetts Institute of Technology. They will present their work at the meeting of the Division of Plasma Physics of the American Physical Society, to be held in Portland, Oregon.

Fusion power is generated when the nuclei of small atoms combine to form larger ones in a process that releases enormous amounts of energy. These nuclei, usually heavier hydrogen cousins ​​called deuterium and tritium, are positively charged and thus feel a strong repulsion that can only be overcome at temperatures of several hundred million degrees. Although these temperatures, and thus the melting reactions, can be produced in modern fusion experiments, the conditions required for a net energy gain have not yet been met.

A potential solution to this could be to increase the strength of the magnets. Magnetic fields in fusion devices serve to keep these hot ionized gases, called plasmas, isolated and isolated from ordinary matter. The quality of this insulation becomes more effective as the field gets stronger, which means that it takes less space to keep the plasma warm. Doubling the magnetic field in a melter reduces its volume – a good indicator of the cost of the device – by a factor of eight, while still achieving the same performance. Thus, stronger magnetic fields make the fusion smaller, faster and cheaper.

A breakthrough in superconductor technology could allow fusion power plants to materialize. Superconductors are materials that allow currents to pass through without loss of energy, but for that they must be very cold. The new superconducting compounds, however, can operate at much higher temperatures than conventional superconductors. Essential for fusion, these superconductors work even when they are placed in very powerful magnetic fields.

Although originally not useful for magnet construction, researchers have now found ways to make high-temperature superconductors in the form of "strips" or "ribbons" to make magnets with unprecedented performance. The design of these magnets is not suitable for fusion machines because they are much too small. Before the new fusion device, called SPARC, can be built, the new superconductors must be integrated into the type of large, powerful magnets needed for melting.

Once the development of magnets is successful, the next step will be to build and operate the SPARC fusion experiment. SPARC will be a tokamak fusion device, a type of magnetic confinement configuration similar to many machines already in operation (Figure 1).

As an achievement similar to the Wright brothers' first flight at Kitty Hawk, the demonstration of a net energy gain, the goal of fusion research for more than 60 years, could be enough to firmly embed the fusion in the plans. national energy markets and to launch commercial development. The goal is to make SPARC operational by 2025.

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