Making The Energy Of The Sun, On A Truck

Lockheed Martin’s Skunk Works, America’s most secret aerospace lab—which gave us the U-2 spy plane and the stealth fighter—has unveiled a ground-breaking design for a nuclear fusion reactor that can fit on a truck.

The device will be the most compact built to date. A working model, the company claims, will be ready in a decade.

The largest of these machines, known as ITER (short for International Thermonuclear Experimental Reactor), under construction in southern France, is, well, very large. When completed, in 2020, it’ll weigh 23,000 tonnes, stand about 100 feet tall and generate 500 megawatts.

The ITER is the world's largest tokamak.
The ITER is the world’s largest tokamak.

The Skunk Works game-changing concept would deliver the same output in a machine, ten times smaller, Thomas McGuire, an aeronautical engineer, leading the team, told Aviation Week.

What’s in the works, presently, however, is a 100 megawatt-reactor, somewhat tubular in shape that’s 23 feet wide and 42 feet long and weighs less than 1,000 tonnes. That’s enough power to illuminate 80,000 homes.

Skunk Works' compact fusion reactor.
Skunk Works’ compact fusion reactor.

Its virtues, being portability and easy assembly, other than generating electricity, it can power long-distance spacecraft, ships, even aircraft, allowing them to fly non-stop, without refueling.

Fusion is what powers the Sun and causes hydrogen bombs to explode with such firepower. But in a controlled manner, traditionally, this process has been brought about in a “tokamak,” a structure built in the 1950s by Soviet scientists. One might think of it, reductively, as a giant, doughnut-shaped, magnetic pressure cooker.

A stream of two varieties of hydrogen gas—deuterium and tritium—is pumped into a vacuum chamber that’s in the shape of a torus or a ring. Electricity is passed through it to heat it. When the gas is impossibly hot, the electrons bounce off their orbits, creating a charged stew of electrons and stand-alone nuclei.

The resultant mixture, called plasma, is then, kneaded by two intense, circular magnetic fields: toroidal (generated by the coils of magnets that surround the torus) and poloidal (produced by the flow of amperes through the plasma).

The pair, working in tandem, creates a thermal environment so infernal and a pressure so crushing that it confines and compresses the nuclei enough for them to coalesce. When they encounter one another, they overcome their mutual electrical repulsion and fuse to form a helium nucleus, which is inert and non-toxic; a destructive neutron; and energy.

In the ITER, the temperature will reach 270,000,000 degrees Fahrenheit, which is ten times hotter than the Sun’s core.

But the drawback of this architecture is that energy-generation becomes a zero-sum game. What comes out is nearly the same as what goes in. It also has a limited room for holding plasma. Aside from these inefficiencies, the physics of the tokamak calls for massive installations that have an astronomical price tag. The ITER is expected to cost $50 billion.

The Skunk Works edition will make improvements on all these fronts—by containing the plasma in a radically different manner.


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