Physics + Math

09
Oct

We’re One Step Closer to Fusion Power

Nuclear fusion—it’s practically the holy grail of energy production. It’s the same process that powers our sun, the primary fuel source is commonly found in seawater, its waste isn’t radioactive, and it doesn’t produce greenhouse gases. It’s pretty close to the perfect base-load power source, one that can be run constantly day and night. The only problem is we haven’t been able to produce a controlled fusion reaction that takes less power to initiate than it produces. So far, fusion has been more of an energy sink than source.

Until now.

Six years ago, I heard a talk from a nuclear physicist from the National Ignition Facility, a research lab located on the edge of the San Francisco Bay Area. He was effusive about the prospects of laser-based inertial confinement fusion, a lesser known approach to fusion that involves zapping small fuel pellets with a laser. (The other approach, the one being tested at ITER in France, is to magnetically contain in a doughnut shaped tokamak a much larger fusion reaction that is initiated by sending electric current through the plasma.) In a few years, the NIF scientist said, their ignition experiments would be producing more energy than they were creating.

His prediction was a bit off, but they’ve delivered. Here’s Paul Rincon, reporting for BBC News:

NIF, based at Livermore in California, uses 192 beams from the world’s most powerful laser to heat and compress a small pellet of hydrogen fuel to the point where nuclear fusion reactions take place.

nif
Preamplifiers at the NIF increase the energy of the laser beams used to initiate fusion reactions.

The BBC understands that during an experiment in late September, the amount of energy released through the fusion reaction exceeded the amount of energy being absorbed by the fuel – the first time this had been achieved at any fusion facility in the world.

Each fuel pellet contains just 0.2 mg of a deuterium-tritium mixture, two isotopes of hydrogen. When the laser hits it, the pellet is heated to 3.3 million K, or about 5.9 million ˚F, which initiates a fusion reaction. The byproduct, in addition to copious amounts of heat, is mostly helium with some tritium, another hydrogen isotope.

Until now, the NIF’s problem was that not enough of the power used to energize the laser was making its way to the fuel pellet. If the efficiency of the system continues to improve, commercial applications would still be decades away. But it’s possible that future power plants could be blasting lasers at one fuel pellet after another, heating steam to turn turbines and power our homes, cars, and more.

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