A Star in a Bottle: Fusion Energy

As we move through winter to spring, many of us feel the early temperature increase. So much so that Austen W. ’30 exclaimed, “It literally feels like spring – this is spring weather!” We shouldn't mistake that global climate change directly translates to an increase in temperature (like the name suggests). More so, it leads to unpredictability in weather and natural phenomena around the world. Globally, everyone is feeling this change in average worldwide temperature. This begs the question, what is the main cause of global climate change? According to the United Nations, “Fossil fuels – coal, oil and gas… [account] for around 68 percent of greenhouse gas emissions and nearly 90 percent of all carbon dioxide emissions.” Steven Cowley, a theoretical physicist and professor at Princeton University, whom I interviewed, offers an eye-opening alternative: an imitation of what’s happening inside of stars, fusion energy – the very reaction happening in the sun shining on our planet right now.

In stars, fusion occurs when two nuclei combine to form a nucleus,  “So you can only do that by getting your fuel, which is two kinds of hydrogen: deuterium (heavy hydrogen) and tritium (which is super heavy hydrogen). When you fuse them, you make helium [and energy]. But in order to make that happen, you need a temperature about 150 to 250 million degrees. It's very, very hot. And holding fuel at that temperature is extraordinarily hot,” says Professor Cowley.  Tritium is a radioactive gas that is unstable in nature. As a result, scientists make it synthetically by exposing lithium-6 to neutrons. Furthermore, the neutrons of a helium atom (created by fusing deuterium and tritium atoms) are what create energy.

Using these concepts, scientists are trying to sustain this fuel – in other words, a sustained burn by using the plasma (a gas of electrically charged particles) of a reactor (to be more specific, a nuclear fusion reactor) – and outputting more energy than its input. Simply put, it’s a bit like placing the sun in a bottle. As you can imagine, that bottle must have the capacity to withstand extreme conditions. For instance, temperature that is roughly ten times the core of the sun. Which is where the tokamak comes into play.

The tokamak design consists of magnetic confinement – where magnetic fields control the plasma (formed by the hydrogen isotopes of deuterium and tritium). An international reactor, the ITER (International Thermonuclear Experimental Reactor), is a great example. Utilizing what will be the largest pulsed electromagnet in the world, it will have the capability to lift a 100,000-ton aircraft carrier! Not only that, “It's aiming to be the first one that makes a sustained fusion burn [when the power created by fusion exceeds the external heating]. So, for maybe 20 minutes … producing about 500 million watts per second,” said Professor Cowley.

Another type of magnetic confinement is “field reverse configurations. It's a very simple configuration. [However],  it's known to be unstable … . But… [the researchers are] investigating that, and they're spending over a billion dollars on… [Helion Energy]”states Professor Cowley. An additional remarkable design is the stellarator, which Professor Cowley adds, “[is] very complicated, because it's three-dimensional." Essentially, it uses magnetic coils in a donut-like shape. Though its energy output is far greater than designs like the tokamak, it has its own difficulties, such as the need for advancement in the research for a sustained plasma burn. Many of you may wonder, “Is there any other design for the confinement of plasma?” Here is where laser inertial fusion, another type of nuclear fusion reactor design, comes into play. “They make a little piece of fusion fuel, and they zap it with lasers. And [the reactor] gets heated to the right temperature, and it explodes, and while it's exploding, it does some fusion,” explains Professor Cowley. Today, scientists are making rapid breakthroughs in fusion – trying to make a feasible and reliable energy source. Turning to AI, a lot of scientists are investigating potential designs for nuclear fusion reactors generated by computers.

As we step into this new era of energy, we can’t help but think of what the future might hold. We’ve seen what global warming can do and, as the crisis escalates, we must think back to energy. Energy is inextricably tied to our very way of being, yet it’s also a big factor to our impending demise. As Professor Cowley said, “one of my motivations is to make sure that we can stop using fossil fuels. Because eventually, we have to stop. Right?”