Lawrence Livermore Labs, and the National Ignition Facility have just announced a major fusion milestone: for the first time, they got more energy out of the reaction than they had to pump into to it to make it happen. For over 60 years, "break-even" has been the dream, where we finally get as much energy out of it as it took to produce it. Researchers have gotten incrementally closer, but until now, no luck.
At the NIF, they pumped in 2.05Mega Joules of energy to create the reaction. They got 3.15 Mega Joules of energy out of it. They considerably exceeded the hoped-for "break-even." They use a process called "laser inertial confinement." Basically, you blast the fuel on all sides, causing it to compress to the densities we find in stars. This particular process uses a "Hohlraum," a small metal cylinder, in which the fuel is suspended. The lasers blast the inside of the metal cylinder, converting the incoming laser light into xrays that blast the fuel pellet. The Hohlraum is destroyed in the process.
Don't go investing in fusion power plants, just yet, though. This method is utterly impractical for generating power. The whole point of this exercise is proof-of-concept. Net energy gain is no longer theoretical. We know now that it can be done. There's a lot more work to bring this into the realm of commercial power production.
And while they're working on this method, the other main contender for fusion is still also being very actively researched: magnetic confinement. These use large machines, loosely based on a design called a "Tokamak," which is like a large, hollow donut. Fill it with hydrogen, heat it up to 300,000,000 million degrees or so, and you get fusion. Right now, though, they are nowhere near break-even. And instead of insanely huge banks of very expensive gigantic lasers, mag confinement uses superconducting magnets to build a magnetic field strong enough to keep the hot plasma from touching the walls of the vessel. Several innovative designs are about to be turned on, and we'll see what happens.
There's a couple of other ideas out there, too. One uses a sphere of molten lead. You spin the superheated sphere, creating a vacuum void in the center of the lead, inject the fuel, then hydraulic hammers spaced around the vessel slam into the lead., collapsing the bubble. The lead transfers the compression to the fuel pellet via the magic of the incompressibility of fluids. Sounds insane, right? But there's a real-world phenomenon that hints that this could work: propeller cavitation in water. Spin a prop in water too fast, and it creates a vacuum bubble. As the bubble collapses, it creates a type of blue light called Cherenkov radiation. The term for that is sonoluminescence. It has also created a few neutrons, here and there, and those are a byproduct of fusion in the isotopes of hydrogen found in water. If you can get that in water at atmospheric pressure, you should be able to get it in liquid lead, at many, many times atmospheric pressure. So the theory goes.
At the NIF, they pumped in 2.05Mega Joules of energy to create the reaction. They got 3.15 Mega Joules of energy out of it. They considerably exceeded the hoped-for "break-even." They use a process called "laser inertial confinement." Basically, you blast the fuel on all sides, causing it to compress to the densities we find in stars. This particular process uses a "Hohlraum," a small metal cylinder, in which the fuel is suspended. The lasers blast the inside of the metal cylinder, converting the incoming laser light into xrays that blast the fuel pellet. The Hohlraum is destroyed in the process.
Don't go investing in fusion power plants, just yet, though. This method is utterly impractical for generating power. The whole point of this exercise is proof-of-concept. Net energy gain is no longer theoretical. We know now that it can be done. There's a lot more work to bring this into the realm of commercial power production.
And while they're working on this method, the other main contender for fusion is still also being very actively researched: magnetic confinement. These use large machines, loosely based on a design called a "Tokamak," which is like a large, hollow donut. Fill it with hydrogen, heat it up to 300,000,000 million degrees or so, and you get fusion. Right now, though, they are nowhere near break-even. And instead of insanely huge banks of very expensive gigantic lasers, mag confinement uses superconducting magnets to build a magnetic field strong enough to keep the hot plasma from touching the walls of the vessel. Several innovative designs are about to be turned on, and we'll see what happens.
There's a couple of other ideas out there, too. One uses a sphere of molten lead. You spin the superheated sphere, creating a vacuum void in the center of the lead, inject the fuel, then hydraulic hammers spaced around the vessel slam into the lead., collapsing the bubble. The lead transfers the compression to the fuel pellet via the magic of the incompressibility of fluids. Sounds insane, right? But there's a real-world phenomenon that hints that this could work: propeller cavitation in water. Spin a prop in water too fast, and it creates a vacuum bubble. As the bubble collapses, it creates a type of blue light called Cherenkov radiation. The term for that is sonoluminescence. It has also created a few neutrons, here and there, and those are a byproduct of fusion in the isotopes of hydrogen found in water. If you can get that in water at atmospheric pressure, you should be able to get it in liquid lead, at many, many times atmospheric pressure. So the theory goes.
