Imagine if we could harness the energy of the Sun right here on Earth. In the blink of an eye, the Sun emits enough energy to power our entire civilization for 4,500 years. Scientists and engineers are striving to replicate this process by creating a miniature star on Earth that could be integrated into our power grid. While we haven’t quite achieved a tiny star in a lab, we do have technology that mimics this process.
Stars are made up of countless particles compressed by gravity into a dense core. This core is so hot and dense that it forces atomic nuclei to merge, forming larger nuclei in a process called fusion. The opposite process, where an atom splits into two, is known as fission. In both cases, the mass of the resulting atoms is slightly less than the original atoms, and this lost mass is converted into energy, thanks to Einstein’s equation. Because the speed of light squared is a massive number, both fusion and fission release substantial energy.
In the Sun, fusion primarily produces helium nuclei. The process begins when two protons fuse to form a deuterium nucleus, which then fuses with another proton to create a helium-3 nucleus. This helium-3 nucleus eventually combines with another helium-3 to form helium-4. However, the initial step is extremely rare, occurring only once in 100 septillion proton collisions. The Sun has so many protons that even rare reactions happen frequently. On Earth, scientists use a more manageable reaction where a deuterium nucleus fuses with a tritium nucleus to produce a helium-4 nucleus and a neutron.
Since the 1930s, we’ve been conducting fusion reactions in particle accelerators. However, these accelerators aren’t designed to capture the energy released; instead, they’re used to produce neutrons for scientific and military purposes. To harness fusion for energy, we need a device that can capture the energy, sustain the reaction, and supply excess energy to the power grid. This is where nuclear fusion reactors come in.
A fusion reactor would generate helium nuclei and neutrons in a superhot core. The neutrons would heat a layer of lithium metal, which would then boil water to produce steam and drive turbines to generate electricity. The helium nuclei would stay in the core, colliding with other nuclei to keep the reaction going and maintain electricity production.
One of the biggest challenges is achieving “ignition,” where the reactor produces more energy than it consumes. A fusion reactor needs a lot of energy to heat the core for fusion. The goal is to reach a point where the fuel is hot enough to start the reaction and release more energy than it takes to maintain that temperature. Stars achieve ignition through immense gravitational forces, but this isn’t feasible on Earth. Instead, researchers use arrays of lasers or methods combining magnets with high-energy particles or electromagnetic waves.
In 2022, scientists at the US National Ignition Facility achieved ignition for the first time using 192 lasers to heat deuterium and tritium to 100 million degrees. This was a significant breakthrough, but we’re still working towards a self-sustaining reactor that produces more energy than it consumes.
Once operational, these relatively small reactors could power a city of a million people for a year with just two pickup trucks of fuel. In comparison, burning about 3 million tons of coal would be needed to produce the same amount of energy. This is the promise of fusion: limitless, on-demand energy with minimal emissions. It’s like having the power of a star right here on Earth.
Engage in a computer simulation that models the fusion process. You’ll manipulate variables such as temperature and pressure to achieve a successful fusion reaction. This activity will help you understand the delicate balance required for fusion and the challenges scientists face in replicating these conditions on Earth.
Participate in a structured debate comparing nuclear fusion and fission as energy sources. You’ll research both processes, their energy outputs, safety concerns, and environmental impacts. This will enhance your critical thinking and ability to articulate scientific concepts effectively.
Work in groups to design a conceptual model of a fusion reactor. Consider the components needed to achieve ignition and sustain the reaction. Present your design to the class, explaining how it addresses the challenges of energy capture and sustainability.
Analyze the 2022 breakthrough at the US National Ignition Facility. Examine the methods used to achieve ignition and discuss the implications for future fusion research. This activity will deepen your understanding of current advancements and the path toward practical fusion energy.
Visit a local research facility or university lab working on fusion technology. Observe experiments and interact with researchers to gain firsthand insights into the challenges and progress in the field. This experience will connect theoretical knowledge with real-world applications.
In the time it takes to snap your fingers, the Sun releases enough energy to power our entire civilization for 4,500 years. Scientists and engineers have been working to build a miniature star here on Earth to integrate into our power grid. Interestingly, we already have a form of this technology, though it doesn’t resemble a tiny star floating in a lab.
Stars are composed of an immense number of particles, which gravity compresses into a super dense core. This core is hot and dense enough to force atomic nuclei together, forming larger, heavier nuclei in a process known as fusion. The reverse process, where one atom splits into two, is called fission. In both processes, the mass of the end products is slightly less than the mass of the initial atoms. However, that lost mass doesn’t disappear; it’s converted to energy according to Einstein’s famous equation. Since the speed of light squared is such a large number, both fission and fusion generate significant energy.
Fusion in our Sun primarily produces helium nuclei. In the most common pathway, two protons fuse to form a deuterium nucleus, which then fuses with another proton to form a helium-3 nucleus, and subsequently fuses with another helium-3 nucleus to form a helium-4 nucleus. However, there’s a challenge—this first step is incredibly rare, with only 1 in 100 septillion collisions between protons resulting in a deuterium nucleus. In the Sun, this isn’t an issue because there are so many protons that even a reaction this rare occurs frequently. On Earth, researchers rely on a more easily reproducible reaction, where a deuterium nucleus fuses with a tritium nucleus to form a helium-4 nucleus and a neutron.
We’ve been conducting reactions like this inside particle accelerators since the 1930s. However, these accelerators are not designed to harness the energy released from these reactions; instead, they are used to generate neutrons for various scientific and military purposes. To use fusion for limitless energy, we need a device that can harness the energy released, channel enough of that energy back into the device to sustain the reaction, and then send the excess energy out to our power grid. For this purpose, we need a nuclear fusion reactor.
Like a particle accelerator, a fusion reactor would generate helium nuclei and neutrons. However, this reaction would occur in a superhot core, and the resulting neutrons would heat a layer of lithium metal. This heat would then boil water, generating steam to run turbines and produce electricity. Meanwhile, the helium nuclei would remain in the core and collide with other nuclei to sustain the reaction and maintain electricity production.
This technology faces many practical challenges, including how to confine a swirling mass of million-degree matter. The biggest hurdle is achieving what’s called ignition. An energy technology is only commercially viable if it produces more energy than it consumes. A fusion reactor requires a substantial amount of energy to heat the core sufficiently for fusion to occur. There’s a tipping point—a moment when the fuel is hot enough to initiate the reaction and release more energy than is needed to reach and maintain that temperature. This is ignition.
Stars achieve ignition through immense gravitational forces, but this approach is not feasible on Earth, as it would require thousands of times the mass of the entire Earth. Therefore, researchers typically rely on vast arrays of lasers or methods that combine magnets with high-energy particles or electromagnetic waves similar to those in microwave ovens. In 2022, scientists at the US National Ignition Facility demonstrated ignition for the first time, using 192 lasers to heat deuterium and tritium to 100 million degrees. While this was a significant advancement, we are still some distance from a self-sustaining, long-running reactor that produces more energy than it consumes.
Once operational, these relatively small reactors could power a city of a million people for a year with just two pickup trucks of fuel. In contrast, you would need to burn approximately 3 million tons of coal to produce that much energy. This is the promise of fusion: limitless, on-demand energy with minimal emissions. True star power, right here on Earth.
Nuclear – Relating to the nucleus of an atom, where nuclear reactions such as fission and fusion occur, releasing significant amounts of energy. – The nuclear forces within the atom’s nucleus are responsible for the immense energy released in nuclear power plants.
Fusion – A nuclear reaction in which two light atomic nuclei combine to form a heavier nucleus, releasing energy in the process. – Scientists are researching fusion as a potential source of limitless clean energy by mimicking the processes occurring in the sun.
Energy – The capacity to do work, which can exist in various forms such as kinetic, potential, thermal, and nuclear. – The energy produced by the fusion of hydrogen atoms in the sun is the primary source of light and heat for our planet.
Reactors – Devices used to initiate and control a sustained nuclear chain reaction, typically used in power plants to generate electricity. – Modern nuclear reactors are designed with multiple safety systems to prevent the release of radioactive materials.
Particles – Small localized objects to which can be ascribed several physical properties such as volume, mass, and charge. – In particle physics, researchers study the behavior of subatomic particles like quarks and leptons.
Gravity – A natural phenomenon by which all things with mass or energy are brought toward one another, including planets, stars, and galaxies. – The theory of general relativity describes gravity as the curvature of spacetime caused by mass.
Ignition – The process of initiating combustion or a reaction, particularly in the context of starting a nuclear fusion reaction. – Achieving ignition in a fusion reactor is a critical step toward making fusion energy a practical power source.
Helium – A chemical element with the symbol He, often produced as a byproduct of nuclear fusion reactions. – Helium is the second most abundant element in the universe and is produced in large quantities during stellar fusion processes.
Technology – The application of scientific knowledge for practical purposes, especially in industry and engineering. – Advances in technology have enabled the development of more efficient solar panels and wind turbines for renewable energy generation.
Electricity – A form of energy resulting from the existence of charged particles, used for power and lighting. – The electricity generated by nuclear reactors is a significant component of the global energy supply.
