Mark Megahan
Nuclear fusion has officially been confirmed to work in the lab. It was reported for the very first time back in December. While once is great, it doesn’t count until the results can be repeated. They just were. As an extra added bonus, the “net energy gain” measured was even bigger this time.
The power of fusion
Over at the Lawrence Livermore National Laboratory in California, where they built a nuclear fusion reactor, they have what they like to call the “National Ignition Facility.”
The office recently accomplished what the name says on the door, “ignition.” What that means to a physicist is just a touch different from the way your car mechanic uses it.
In the nuclear fusion world, ignition is the point where the unit produces more energy than what’s being pumped in to make it work.
We’re still a few years away from harnessing it for electricity but the July 30, 2023 repeat performance was a major milestone.
As soon as the team of highly trained and specialized researchers achieved the near impossible, Energy Secretary Jennifer Granholm rushed to pat them on the back for it.
“This is a landmark achievement for the researchers and staff at the National Ignition Facility who have dedicated their careers to seeing fusion ignition become a reality, and this milestone will undoubtedly spark even more discovery”
Inertial confinement method
There are two main ways to produce a captive star in the lab and the NIF guys use the older, less popular method. Called inertial confinement, it’s a lot more like a bomb in a bottle than a power plant.
The more modern option, “magnetic confinement fusion,” involves heated plasma “confined within a torus-like shaped device called a tokamak, and magnetic fields are used to keep the plasma confined.” It might be newer and cool but doesn’t work yet. The bomb in a bottle method does.
The approach used by the National Ignition Facility uses an array of lasers to bombard a small pellet, heating it “to tremendous temperatures, triggering fusion reactions inside this hot, hydrogen-rich volume.” The experts say it’s a lot like like “a very, very small explosion.”
It’s the mass of the surrounding material that provides “inertia” at the outer layers of the pellet to confine the violent reaction, “enabling it to last long enough to achieve a net energy gain.”
For practical purposes, that needs to happen either steadily or repeatedly in such a way that normal engineers can use the power to spin turbines. Initial data from the July experiment “indicated an energy output greater than 3.5 MJ.” That’s more power than the December success.
“The 5 December experiment used 192 laser beams to deliver more than 2 million joules of ultraviolet energy to a deuterium-tritium fuel pellet to create so-called fusion ignition.” That try achieved “an output of 3.15 MJ” of energy “from the delivery of 2.05 MJ to the fuel target.“
