The World’s Largest Reactor’s Giant Magnet

The total magnetic field energy of the magnet system used for the ITER fusion reactor in France is up to 41 gigajoules, which is 250,000 times stronger than the Earth’s magnetic field. ITER, the world’s largest fusion experiment, has made significant progress towards operational status with the delivery of all the special magnets needed to build the reactor core in southern France. This milestone marks the completion of a two-decade long design process that involved manufacturing components across three continents.

As the world seeks more sustainable ways to generate carbon-free energy, fusion technology offers a promising solution that can be controlled as needed. Recent advancements in fusion research have shown the potential for extracting energy from fusion reactions. Over 30 countries are collaborating on the construction of the International Experimental Thermonuclear Reactor (ITER) in France, which aims to demonstrate the feasibility of fusion power.

ITER’s design features a tokamak reactor that uses hydrogen to create plasma in a doughnut-shaped vacuum chamber, simulating the conditions at the core of the Sun. The plasma is heated to an extreme temperature of 150 million degrees Celsius to initiate fusion reactions. To confine the plasma within the reactor and control its behavior, giant superconducting magnets are used. These magnets utilize niobium-tin and niobium-titanium as fuel, with an intricate cooling process to facilitate superconductivity.

The design of the ITER reactor includes various types of superconducting magnets strategically placed to form an invisible magnetic cage that contains the plasma. D-shaped magnets, horizontal surrounding magnets, and a central solenoid all work together to create and control the plasma currents within the tokamak. The magnetic fields produced by these magnets are incredibly strong, with a total energy of 41 gigajoules, vastly surpassing Earth’s magnetic field strength.

The manufacturing process for these magnets involves winding niobium-tin filaments with copper wires, encasing them in steel housings, cooling them to superconducting temperatures, and assembling them into intricate structures. Once operational, the ITER fusion reactor is expected to produce 500 MW of power, with 200 MW of continuous electricity feed into the grid, providing energy for approximately 200,000 homes.