Merry Christmas everyone! Let’s talk about nuclear fusion (tis’ the season to fuse atoms)
About two weeks ago, Lawrence Livermore National Laboratory confirmed it had finally achieved fusion ignition. Scientists hailed it as a major breakthrough. One we’d spent sixty years and billions of dollars to reach. But what is ignition, and what does this have to do with my book series?
In Scribes’ Descent, nuclear fusion is the main power source on planetary surfaces. On Imna, the first commercial fusion plant goes online in 7939AD–387 years prior to the events in the book. This makes fusion a mature tech in Mallory’s day, taken for granted and made compact enough to fit in a small room.
By contrast, in our world, the equipment that achieved ignition occupies a ten-story building as big as three football fields.
This fusion reaction only lasted a billionth of a second and was grossly inefficient. More on that later. So, we still have problems to solve before we can power our toothbrushes and kitty cameras with it. But we have made big progress. We’ve achieved ignition. But what is that?
First, let’s look at how fusion works–a simple explanation for the non-physicists among us. Starting with how the very concept of fusion seems unlikely at first glance.
Hydrogen atoms have one proton in the nucleus, and protons are positively charged. We know from playing with magnets that like charges repel. This happens because of the electromagnetic force. But how would you force protons to stick together in spite of that repulsion? If you can smash atoms close enough together, something called the strong force takes over. It’s 100 times stronger than the electromagnetic force, so it wins. Problem is, the strong force only acts across extremely short distances.
Need a visual? Imagine you and your special someone enter a room from opposite sides, and that room is filled with toddlers who push you and your partner away from each other. But a beefy wrestler stands in the middle of the room. If you two can each shove into the center, the wrestler reaches out with his T-Rex arms and pulls both of you into a loving headlock (and you two get smooshed into a single human being). Safe in his armpits, the toddlers are too weak to pull you apart! In this example, the toddlers are the electromagnetic forces, and the wrestler is the strong force.
So how do you get atoms close enough for the strong force to take effect? Among the different ways, Livermore Lab researchers used inertial confinement. They aimed powerful lasers at a tiny pellet made of deuterium and tritium, which are heavy forms of hydrogen. And yes, we’re talking about James Bond movie lasers. The most powerful lasers in the world, so don’t let your cats near them. The pellet’s surface heats into a plasma that explodes evenly in all directions. Then, in an equal-but-opposite reaction, the inside of the pellet implodes, cramming the hydrogen atoms into an extremely tight space. If all goes well, they get close enough for the strong nuclear force to bind them together. Two hydrogen atoms merge into a single helium atom, and this releases a LOT of energy. Why? Because some of the mass of the fused atoms converts into energy, according to the famous equation e=mc^2. And that energy output is the whole point of building a fusion reactor.
Short explanation: you and your girlfriend use laser-powered jetpacks to blast through a room of toddlers so the Hulk can smash you together hard enough to turn part of your bodies into energy. 🙂 Now if your friends ask you to explain inertial confinement fusion, you’ll know exactly what to say!
What’s this stuff about ignition, then? That just means the energy released by the reaction has exceeded the laser energy needed to make the fusion happen. In the case of the Livermore Lab, they put in 2.05 megajoules into the lasers and got out 3.15 megajoules of energy. (a net gain of over 50%)
Sounds good, but the lab used about 300 megajoules of electricity to produce those 2.05 megajoules’ worth of lasers.
300 megajoules->2.05 megajoules of lasers->3.15 megajoules of energy produced
A commercial plant would go broke with this level of inefficiency. To make inertial confinement fusion work, we must spend less power to make the lasers, create more power, and sustain the reaction longer. However, there are many other fusion reactor types being developed, some of which may prove more practical. If you want me to discuss those in a future newsletter, let me know.
Comments or questions? Reply to this email! Also reply if you’ve built a functioning fusion reactor or want to share photos of your kitty surveillance cameras. I know you people have them! 🙂
Want to read even more Christian-based sci-fi? Check out Rachel Newhouse’s Red Rain series! I’ve read and reviewed nearly the whole series and it is good. She just released a collection with 6 of her books combined:
You can find it on Amazon.
Writing update: I’m still plugging away at Scribes Aflame (book 2). It stands at 61,000 words, and I have at least another 40,000 words to add. If you’ve read book 1 and want to beta read book 2, reply and let me know.
See you next month,