Nuclear Fusion Breakthrough

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TIL about the recent breakthrough in nuclear fusion. In case you missed it, here is a quote from the announcement on website:

“The U.S. Department of Energy (DOE) and DOE’s National Nuclear Security Administration (NNSA) today announced the achievement of fusion ignition at Lawrence Livermore National Laboratory (LLNL) — a major scientific breakthrough decades in the making that will pave the way for advancements in national defense and the future of clean power.”

This sounds like great news! Let’s look into it more closely.

What is nuclear fusion, to begin with? In layman’s terms, when you stick together two atomic nuclei, they form a heavier nucleus. That’s it. This process is called fusion. (Not very different from how Goten and Trunks fuse into Gotenks.) The reason why it is interesting is that this process releases large amounts of energy. This is because the resulting nucleus has less mass than the sum of the two initial nuclei, and to compensate for the loss in mass, a large amount of energy is released following Einstein’s famous equation, E=mc^2.

But why is the resulting nucleus’s mass less than the total mass we began with? Why isn’t it the same or perhaps even heavier? This is because the resulting nucleus is more “stable” than the initial two nuclei, lowering the total energy and mass of the atom. However, this isn’t always the case. If the resulting nucleus is less stable, then the fusion process would require energy instead of releasing it. In fact, as we go up the periodic table, fusing elements releases energy only until iron. After that, fusing elements requires energy, and breaking elements releases energy; this process is called fission. That’s why you wanna fuse light nuclei and break heavy ones to get energy out of the system which could then be converted into electricity to keep our houses warm. This is also the reason why iron is naturally found in abundance because it’s the chillest most stable dude in the universe, with a solid iron core… surface… and everything else in between. This is also the reason why elements heavier than iron, such as gold, platinum, and silver are formed under extreme conditions, like in the belly of a dying star that explodes into a supernova or when two dense neutron stars spiral into and obliterate each other, because they require immense amounts of energy. Even our Sun, the mightiest celestial body in our solar system, which everyone bows before and revolves around, isn’t quite powerful enough to form these heavy elements.

Speaking of the Sun, there is fusion happening inside it all the time, although not as much per unit volume as one might think. Surprisingly, by volume, even your body produces way more heat than the Sun. So, if you were to rub some Sun stuff on your face, it would actually feel cold to you as it would steal heat from you. But wait, don’t we know that the Sun is extremely hot? Yes! The reason it is hot is simply because it is massive. Compared to its volume, its surface area is not nearly large enough for all the heat to escape, so it keeps getting hotter. It’s for the same reason that if you were to shrink an elephant to the size of a mouse, it would die of hypothermia thanks to its massive (relative to its body) ears dissipating heat, and of course, you. To recap, the Sun is indeed very hot even if the energy produced per volume is lower than a compost pile. What’s interesting is that man-made fusions have achieved way higher temperatures. For comparison, the current world record of sustained high temperature in a nuclear fusion is 150 million degrees Celsius compared to the mere 15 million degrees Celsius at the core of the Sun. Ever wondered how researchers even sustain such a high temperature without burning down the whole planet? If so, you’re not alone. I asked ChatGPT (the modern version of “I looked it up”) and apparently, they use powerful magnetic fields to contain the hot stuff, called plasma, in a vacuum. This way, the plasma is levitated and doesn’t come into contact with any surface, not even air, and is then encased with specialized material made of tungsten and beryllium that can withstand extreme temperatures. So, overall, it’s safe to say that in some sense at least, mankind has already surpassed the fusion taking place inside the Sun.

Clearly, fusion is not something new; it was achieved back in the 50s. And the world’s first laser-induced fusion was achieved in 1974, when high-energy lasers were used to reach the high temperatures and pressures needed for fusion to occur. This time, for the first time, they were able to produce more energy from fusion than the laser energy used to drive it. For the first time, there was a net positive outcome from the system. They got more energy out than what they had put in, which theoretically means infinite free energy because you could take the extra energy you got from the system and channel it right back in to get even more extra energy. This might be tingling your “spidey-senses.” How on Earth does it not defy the basic law of conservation of energy, right? Well, the energy is still conserved. The missing part is the additional fuel that goes into the system. As we saw earlier, two nuclei fuse together to form a heavier, more stable nucleus, and the process releases energy. The less stable nuclei are the fuel. It’s the stored potential energy in the form of strong nuclear bonds between the protons and the neutrons in the nucleus of an atom that we are essentially mining! :’)

The good news is that the fuel is hydrogen, which there is no scarcity of and is found everywhere, in the oceans, atmosphere, and on land. And even better news is that the byproduct of fusing hydrogen atoms is helium, which is an innocuous, inert gas, making fusion an excellent source of clean energy. Compare this with fission for a moment. The fuel is a radioactive element, uranium, which is hard and expensive to mine and process, and the byproducts are harmful radiation and radioactive isotopes that are difficult to dispose of.

One can imagine the immense potential of fusion-based clean energy if we could truly harness it. It could completely change the world as we know it, altering the geopolitical landscape forever as countries would no longer be reliant on each other for access to oil and other natural resources. Imagine how the Russia-Ukraine war would have played out differently. The advent of fusion-based clean energy would likely drive down electricity prices dramatically and lead to a race to electrify all sectors currently powered by combustion or that could be powered by electricity. Solutions for decarbonizing the atmosphere would become more economical, potentially giving us a shot at reversing the negative effects of climate change. Not to mention all the second-order effects that would accelerate research in AI and medicine thanks to the reduced cost of computation. On the other hand, Bitcoin mining would probably increase too, as people would only be bound by the number of GPUs they own instead of the soul-crushing electricity bills that all New Yorkers are familiar with, bitcoin or not. But overall, it’s clear that fusion-based clean energy will have largely positive effects on society.

So, how far are we from this utopian world? Here is a quote from a recent New York Times article covering the breakthrough:

“Although the latest experiment produced a net energy gain compared to the energy of the 2.05 megajoules in the incoming laser beams, NIF needed to pull 300 megajoules of energy from the electrical grid in order to generate the brief laser pulse.”

Basically, when considering a larger system that includes the electricity consumed by the laser gun and not just the energy delivered by the laser beam, the experiment consumed way more energy than it produced. This doesn’t necessarily invalidate the breakthrough, as the main point is that the researchers were able to use laser beam energy to create a tiny amount of fusion and then use this tiny amount of fusion to create a small amount of fusion, to achieve net energy gain. The next steps would be to use this small amount of fusion and repeat the cycle to create medium and large amounts of sustained fusion that could be housed in a power plant to generate electricity. So, the excitement around this breakthrough is justified, but the above quote does give us an idea of how far a fusion-based power plant is from becoming a reality. The estimate is still a few decades from today, keeping it in the realm of distant future technologies for just a little longer.