Achieving Ignition: A Milestone for Nuclear Fusion

Jade Lee '24

On December 13, 2022, the US Department of Energy announced something that is the beginning of a new future in energy. A milestone so tremendous, it was considered impossible in the past: a nuclear fusion reaction with net energy gain.

Maybe you’ve heard about nuclear fusion in a science class, but you probably don’t remember the exact details. But don’t worry, understanding nuclear fusion isn’t as difficult as you may think. 

Nuclear fusion occurs under extremely high temperatures where the nuclei of light elements, such as hydrogen, merge together to create heavier atoms with a new nuclei. This merging releases a tremendous amount of energy, four times up to what nuclear fission, a reaction where the nuclei of heavier elements are split into lighter ones to produce energy, can release [1]. You can probably recognize nuclear fission to be the very reaction that drives our nuclear power plants, which produces about 20% of energy used in the US [2].

We actually also see nuclear fusion in action every day. Just look up into the sky, day or night, and you’ll most definitely recognize the existence of both the sun and the nighttime stars (disclaimer, do not look directly at the sun). Stars utilize nuclear fusion as their main energy source to prevent collapsing in on themselves. At their core, hydrogen nuclei are continuously merging with each other to produce helium, and the energy produced actually pushes back against the inward force of gravity [3].

Scientists have been aiming to create ignition, a condition where the whole process becomes self-sustaining through a chain of fusion reactions. This also means that the energy released from the reactions is greater than the energy required to produce the reactions: a net energy gain. However, ignition is much harder to reproduce in a lab setting, especially in comparison to stars, where ignition happens every second and ginormous gravitational forces are incredibly ideal for triggering the reaction. Even nuclear fusion is difficult to achieve as it requires nuclei to overcome considerably strong repulsive electrostatic forces between them [1]. 

The concept of nuclear fusion has been around for nearly 70 years. Starting in the late 1940’s, the earliest researchers were quick to discover the difficulties of reproducing nuclear fusion, let alone developing it for practical use. Besides how impossible it was to recreate the reaction, they also lacked the necessary technology to try [4]. 

Yet, the benefits were too priceless to simply give up. It has become increasingly more vital for scientists to find an alternative energy source to mitigate the rise of climate change and pollution, which commercial nuclear fusion energy could solve. Nuclear fusion energy is much safer than the energy produced from nuclear fission reactions in nuclear power plants, which produces radioactive waste and is difficult to clean up [5]. Even in comparison to fossil fuels, nuclear fusion energy is far more abundant and long-lasting. Its potential to provide endless energy to the entire world without destroying the environment was simply too promising to researchers. 

With all of this in mind, researchers all over the world pursued nuclear fusion for many years. [6]. Unlike the researchers of the past, however, scientists now have better access to creating the conditions right for nuclear fission, especially with the invention of the laser, which provides enough energy for the reaction to happen [4].

And now, we have a new milestone in our hands. 

In California on December 5, two heavy isotopes of Hydrogen, deuterium and tritium, were heated by 2.05 megajoules of energy with lasers to trigger nuclear fusion. Surprisingly enough, the reaction produced 3.15 megajoules of energy, more energy than the energy initially used [7]. 

This is the first time in history that scientists were able to trigger ignition. 

The net release is actually not a lot of energy though, it’s actually close to about how much energy it takes to boil a full kettle of water [6],  but nonetheless, scientists and researchers all around were delighted to see the long-awaited milestone finally happen. 

“This monumental scientific breakthrough is a milestone for the future of clean energy,” said the senator of California, Alex Padilla. Jennifer M. Granholm, the U.S. Secretary of Energy, described it as “a landmark achievement for the researchers and staff at the National Ignition Facility who have dedicated their careers to seeing fusion ignition become a reality, and this milestone will undoubtedly spark even more discovery”  [8].

From now on, scientists can shift their focus to actually converting the released energy to viable forms for things like electricity, and figure out a way to engineer net energy gain efficiently [6]. 

Although we’re probably still years away from achieving commercialized nuclear fusion energy, the future, where energy is sustainable and clean, is looking increasingly brighter.