Earlier this month, the director-general of the International Thermonuclear Experimental Reactor (ITER) announced that construction of the project had reached the halfway point. It’s an important milestone for the multi-billion-dollar facility being constructed in southern France. The goal is to begin generating plasma, an essential component of nuclear fusion reactors, by 2025.
ITER (Latin for “Way”) is a partnership of 35 countries, all hoping to share in the scientific rewards. “This gives us confidence as we face the remaining 50 percent,” Dr. Bernard Bigot of ITER told the journal Live Science.
When completed, the plasma circulating in the core of the reactor will be 270 million degrees Fahrenheit, or about ten times hotter than the sun. The massive superconducting magnets surrounding the core will be cooled to minus 452 degrees, as cold as the depths of space. “So many of the technologies involved are really at the cutting edge,” Bigot said.
Unlike traditional nuclear reactors, which generate power by splitting larger atoms into smaller ones, the ITER fusion reactor will combine hydrogen isotopes (deuterium and tritium). At extremely high temperatures, hydrogen gas can become plasma — sometimes called the fourth state of matter — where the electrons are separated from their nuclei.
Most experimental fusion reactors use a tokamak, which is a superheated donut-shaped device surrounded by superconducting magnets that control the plasma inside. It’s basically a steam engine — the heat generated by the reaction is absorbed by the walls of the reactor and used to produce steam for electricity generation.
It takes a lot of power to create fusion, and the challenge is to make the reaction self-sustaining so it produces more power than is put into it. There are other fusion reactors in operation, but ITER is the largest, with ten times more plasma capacity than any other reactor. Still, it’s just a prototype. If successful, commercial fusion reactors would produce 10 to 15 times more power.
Wendelstein 7-X, a fusion reactor in Germany, recently went online for the first time, and may be able to generate self-sustaining plasma. However, Jonathan Menard of the Princeton Plasma Physics Lab told Business Insider that it’s unlikely to generate enough surplus energy to create electricity.
Another experimental concept envisions fusion reactions powered by lasers, but most scientists think the ITER project is the most promising. “So far, the laser based systems are pretty inefficient and we think the [plasma] fusion systems are closer to having net energy,” Menard said.
ITER is on schedule for “first plasma” in 2025, and by the 2030s they hope to generate ten times more power than goes into it, laying the groundwork for a clean energy revolution. “With ITER and fusion energy, we have a chance to leave a powerful and positive legacy for future generations,” Bigot said.