This Massive 60-Foot Magnet Could Be The Key To Fusion Energy

For years, scientists have been trying to replicate the concept of nuclear fusion — the phenomenon that keeps the Sun and other stars alive — and turn it into a working reactor on Earth that can provide clean and relatively limitless energy. Building such reactors is a massive challenge, but a special kind of superconducting magnet could help solve the infrastructure challenge and make them a reality in the coming decades.

In March, the Oak Ridge National Laboratory announced that the US had made the final delivery of magnet components that will support the 60-foot-tall central solenoid at the heart of the International Thermonuclear Experimental Reactor (ITER) in France. Once assembled fully, the ITER will demonstrate a power plant-level controlled nuclear fusion for a few minutes. The central solenoid is the key part of this reaction, and must be linked to a support structure consisting of magnetic modules that each weigh an astounding 121 tons.

The entire structure built around the central solenoid is extremely crucial and must be assembled with millimeter-level accuracy. Additionally, it must be extremely resilient so that it can handle the immense force generated by the central solenoid. Kevin Freudenberg, engineering technical director at US ITER, says the vertical force hitting the module could be twice that of a space rocket engine at take-off.

The 60-foot central solenoid is said to be the heart of the ITER, and its sixth (and final) component was assembled in April. But why do you need a magnet strong enough to levitate an aircraft carrier when the project is essentially about harnessing the power of the Sun? The central element of the ITER is a machine called a tokamak, which requires strong magnetic fields to control the super-hot plasma that eventually drives the fusion reaction to produce energy.

To fully understand the importance of magnets, one must go back to the basics. In a nuclear fusion chamber, the fuel is a mix of hydrogen isotopes (viz. deuterium and tritium). Then, electrical current is passed in the chamber to ionize the gaseous mixture, which turns it into a hot plasma, which leads to the merger of atoms (aka fusion) and releases a tremendous amount of energy. But why magnets, one might wonder?

The plasma is hot — roughly 150 million degrees Celsius. According to the team behind ITER, that's approximately ten times hotter than the core of the Sun. The material must be handled with extreme care, and the best way to do it is by using magnets to create a field that contains this super-hot plasma and also controls its flow. That control is achieved using two magnetic fields: a toroidal field generated by magnetic coils and a "poloidal" field created by the central solenoid.

Interestingly, ITER's central solenoid is the largest magnet ever built with superconductivity properties. The magnetic field generated by it is roughly 280,000 times higher than that of Earth's natural magnetic field. As far as the energy output goes, the net gain offered by the fusion reactor is estimated to be roughly 500 megawatts, ten times higher than the input power required to generate the plasma for initiating the atomic fusion.

The ITER initiative is a joint collaboration of over 30 countries across multiple continents, but it's not really a commercial project. Instead, it's more of a technical demonstration that will prove the feasibility of controlled nuclear fusion at a scale that can match, or exceed, the output of conventional nuclear power plants or those burning fossil fuels.

However, a technical project of such magnitude is no easy feat. Last year, the organization behind the project announced that its original target of igniting plasma in 2025 is not achievable. The team is now hoping to achieve full plasma current generation in 2034, atomic fusion in 2035, and an operational deadline of 2039.

The benefits, however, will far outweigh the delays. According to the International Atomic Energy Agency, nuclear fusion will generate four times more energy than fission per kilogram of fuel, and four million times more energy than burning coal or oil. In addition to filling the energy requirements of modern civilization, defense experts are also hopeful that nuclear fusion will be the key to aerial superiority in the near future.