(Inside Science) -- What’s 7 feet tall and 14 feet wide and weighs 125 tons? A giant magnet -- one of the largest ever built -- and there are seven of them. The magnets are part of a huge global project involving 35 nations and billions of dollars, all to reproduce the sun’s boundless energy.
John Smith of General Atomics in San Diego, California, explains what fusion is: “Fusion is duplicating what happens on the sun here on earth.”
And that’s no small task -- but scientists across the world are up for the challenge. And one very important component of making fusion happen on earth requires a gigantic magnet -- one that weighs almost as much as a plane.
“What we’re making here is the main -- one of the three large magnet systems for ITER, superconducting magnet systems. The central solenoid is our exact project,” said Smith.
ITER is a nuclear reactor project being built in France. The machine designed to harness the fusion energy is called a tokamak, and at the core of the tokamak is a central solenoid -- or a giant superconducting magnet of coils -- considered by some to be the central heartbeat of the entire system.
Scientists and engineers at general atomics are assembling seven total coils for ITER, six to be installed and one extra. Altogether ITER’s magnet systems use over 60,000 miles of superconducting wires made of niobium-tin -- enough to go around the globe twice!
“Here in San Diego we make the individual modules. So, when the central solenoid is fully assembled, it’s over 50 feet tall and 14 feet in diameter,” said Smith.
When the entire system is complete, the coils, including the solenoid, will be placed around plasma inside the tokamak. The 10,000 tons of coils will be able to store more than 50 billion joules of magnetic energy inside them -- more than ten times that of a bolt of lightning. The magnetic field generated by the coils will be used to start up and control the plasma where nuclear fusion happens.
Creating and stabilizing the plasma is one of the goals of the experiment. With temperatures reaching as high as 150 million degrees Celsius, or 10 times hotter than the center of the sun, the plasma floats inside the tokamak in the shape of a doughnut.
To maintain the plasma, the coils must work together and generate an overall magnetic field that can let the fusion occur, and at the same time stay confined inside the tokamak.
The ITER project has been ongoing for over 12 years. The coil production part is about a quarter of the way done.
“Our fabrication process for each coil takes approximately two years. So, for the seven coils we will be about four years in production. Our last coil is currently planned to ship in 2021,” said Smith.
Progress on ITER has been a long process, and it’s been behind schedule and over budget. But scientists have been working towards getting it back on track.
“I think the progress could be much more rapid had the funds been available to solve the engineering and technological problems,” said Smith.
Smith, who has been working on the ITER project for over a decade, thinks it will all be worth the wait.
“But the limitless energy supply, the green nature of the fusion energy, the potential of it is tremendous, and that’s why we should continue to pursue it,” concluded Smith.