32 November/December 2021

// B Y C A R O L I N E D E L B E R T //

Machines

COURTESY GENERAL ATOMICS

7

The superconducting electromagnet is the

“beating heart” of the ITER tokamak—a mag-

netic confinement device that produces controlled

thermonuclear fusion power. If you think of ITER

as a massive electrical transformer, the Central

Solenoid is the “primary,” meaning it will guide

15 million amps of electrical current into the

doughnut-shaped tokamak body, helping to shape

and stabilize the sun-hot plasma inside.

While the giant ITER reactor is more of a

prototype for future large-scale tokamaks, and

will not generate electricity, it will be a means

How Do You

Build the

World’s

Largest

Magnet? It’s

Complicated

T

HE WORLD’S LARGEST AND MOST POW-

erful magnet, the “Central Solenoid,” is

finally here—or at least, the first piece

of it is. Fully assembled, it will be 59 feet

tall, 14 feet wide, and weigh about 1,000

tons, meaning the decade-in-the-making

magnet will be truly massive. Appropri-

ately, it will find a home in southern France at the

world’s largest fusion reactor, the International

Thermonuclear Experimental Reactor (ITER),

by 2023.

Constructing a magnet of this magnitude is

one huge job. Engineers and technicians at Gen-

eral Atomics in San Diego have spent over half

a decade designing, fabricating, and testing the

various components of the Central Solenoid in its

production facility—and that’s only half of the

battle. Transporting each piece of the magnet is

a Herculean endeavor in and of itself, requiring

custom-built roads and cranes to haul them.

It makes sense when you consider the scope of

the magnet. “If you think about an aircraft car-

rier, which weighs...about 225 million pounds, the

Central Solenoid will generate enough magnetic

force that it would be able to lift it six feet into the

air,” says John Smith, director of engineering and

projects for General Atomics.

In Aug ust, the magnet’s first module arrived in

France, but the Central Solenoid will eventually

consist of six pieces in total. Each module is seven

feet tall, 14 feet wide, and 250,000 pounds. Once

complete, engineers will stack and link the mod-

ules together at the center of the reactor.

This machine’s

magnetic force

will reach

a strength

280,000 times

stronger

than Earth’s

magnetic field.