Jun 16, 2021
Nuclear Fusion: What it is and how it Works
Everything needs energy. It powers cars, TVs, factories, etc. There are a lot of different ways to get that energy. Fossil fuels, wind and solar, hydroelectric, geothermal, even nuclear power. They all have their pros and cons, but nuclear power, or nuclear fission, is the best energy wise. 20% of all of America’s energy comes from only 94 nuclear power plants. In fact, one nuclear power plant produces as much energy as 3.125 million solar panels. But nuclear fission doesn’t come without its drawbacks. It takes a lot of time and money to permit and build a power plant. Not to mention that nuclear fission produces hazardous waste, and enriching Uranium is dangerous. But there is an energy source that comes with all the pros of nuclear fission, with none of the waste: nuclear fusion. While nuclear fusion reactors are still being worked on, people have high hopes for what they can accomplish. But how does nuclear fusion work?
How it Works
Nuclear fusion may sound complicated, but it is actually quite simple to understand. In a nutshell, nuclear fusion is when two very excited, very energetic, and very hot atoms collide, forming one bigger molecule while releasing energy and some subatomic (or smaller than atom) particles (Linquip). It takes a lot of energy to perform nuclear fusion, because of the Coulomb force. The Coulomb force, based off Coulomb’s law, is when two atomic nuclei with similar charges repel each other, while nuclei with opposite charges are attracted to each other. This is like how magnets work. When both of the North, or both of the South, sides of magnets are near each other, they will repel one another. But if both a North and a South end of a magnet are close together, they will attract. According to Coulomb’s law, this is how it is for atoms as well. Because of this, to get similar atoms to fuse they would either have to be going super fast, or would have to be heated up to really high temperatures.
Nuclear binding energy is the smallest amount of energy needed to break down the nucleus so the atoms can fuse. According to Linquip, “The denser the element, the more energy is needed to disintegrate its nucleus.” So larger elements would not work well to fuse, although small elements like hydrogen and helium are perfect.
What happens during fusion? Say the reactor is using hydrogen or helium. When the two atoms combine, the new atom has extra energy and some spare neutrons, making it unstable. Because atoms don’t like being unstable, they try to go to the nearest point of stability by releasing excess energy. To do this, the atoms get rid of the extra neutron(s) with its remaining energy. The remaining energy is what will be harvested.
Barriers to Overcome
While nuclear fusion would be a good energy source to have, there are some technical barriers that must be overcome before it is ready for wide-scale development. Energy, material requirements, and reactor design all are important for making a working fusion reactor.
Amount of Energy Needed
To start a nuclear reaction, a lot of energy is needed. In fact, the reactor would have to be at least 100,000,000˚C. That’s a little more than 6 times the temperature of the Sun’s core. To keep the reaction going, there would have to be a lot of extra energy. However, enough excess energy should be created after the first reaction to help the other atoms fuse. Nuclear fusion reactors do exist, but they use more energy than they produce.
Material Requirements
Another tough barrier to overcome is what the reactor will be made of. Known materials won’t work, and will warp from the high temperature. Also, fusion reactions “produce high-energy neutrons that hit the reactor walls” (ScienceABC). The wall that is hit by the neutrons is called the first wall, and when constantly hit with the neutrons, the first wall becomes radioactive, due to a reaction that happens between the neutrons and the metal. Until good materials can be found, decent fusion reactors are not going to be a thing.
Reactor Design
Thankfully, this next barrier has almost been mastered by engineers and scientists alike. To contain nuclear fusion reactions, the container would need to be intricate and densely-packed. Most companies that are working on fusion reactors use a design called a tokamak, which is similar to what a donut looks like. During the reaction in the tokamak, a gas is pumped into the chamber, and an electric current runs through it, forming plasma. The plasma forming is not the problem, but the plasma creates its own electromagnetic current, disrupting the magnetic field caused by the materials in the tokamak. As of now, there is no good way to contain the plasma.
What Companies are working on Nuclear Fusion?
Many companies are working on creating nuclear fusion reactions, and it’s no wonder why. It’s environmentally clean, only needs water and/or fuel pellets to work (depending if lasers are being used or not), and is cheap. Here are three projects, from CBSNews, that show a lot of promise.
The National Ignition Facility (USA)
The NIF initially proved that using lasers to cause nuclear fusion could be a solid idea. They plan to fire 192 lasers at fuel pellets, causing its core to undergo nuclear fusion. Because of this, when they started in 2009, they were the world’s most watched nuclear fusion project.
International Thermonuclear Experimental Reactor (France)
ITER is trying to prove that nuclear fusion is a good source of energy, to overcome the world’s dislike of anything “nuclear”. It is currently under construction in the south of France, and was funded by seven unlikely allies: China, the European Union, India, Japan, Korea, Russia and the United States. ITER is based on the toroidal tokamak design, and is not focused on making energy itself, but will resolve scientific and technical barriers.
MIT’s Levitating Dipole Experiment (USA)
The Levitating Diploe Experiment (or LDX) is MIT’s attempt to create a new design for nuclear fusion reactors. The LDX will be similar to the normal tokamak design, but instead the magnets will be inside the container. This will make the plasma interact differently, including an unexpected density. Also, the tokamak chamber will float.
Conclusion
Nuclear fusion is amazing. It is infinitely more powerful than some of our current energy sources, and it environmentally clean. While it may sound complicated, the basics are quite easy to understand. And while there are still some barriers that need to be overcome, several companies have already been working on them. Nuclear fusion could change the world.
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