The History of Nuclear Fusion: The Big Picture
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Nuclear fusion is a type of nuclear energy that offers the prospect of a clean, safe, and virtually inexhaustible energy source for us and future generations. Despite being held back thus far by unresolved engineering challenges, the nuclear fusion industry has had technological breakthroughs in recent years. So, we had to ask: What is the history of nuclear fusion?
Nuclear fusion began in 1934 when it was first demonstrated in a laboratory setting. Then, the invention of the stellarator and tokamak fusion reactors in the 1950s spurred research into fusion’s commercial viability. It is still being researched and does not yet supply energy to our power grid.
One way to combat the current global climate crisis threatening Earth’s environmental, economic, and social health is to transition away from traditional fossil fuels and toward cleaner energy sources, such as nuclear energy. Keep reading to learn how nuclear fusion came to be, who and what pioneered its development, how effective it has been thus far, and what the future of nuclear fusion could entail.
Here’s the History of Nuclear Fusion in a Nutshell
Nuclear fusion, one of two ways to produce nuclear energy, is the generation of energy produced when lighter atoms are combined or fused to create larger and heavier atoms.
“Nuclear fusion: the process of joining two nuclei to produce energy.”
Cambridge Dictionary
Nuclear fusion is still very much in the research and development phase. The fusion process is very hard to control within a laboratory setting. More research and development still needs to be done to determine if fusion could be another viable energy source.
Nuclear fusion has gone through three distinct development phases in its development:
- Early market formation and innovation: The early history of nuclear fusion dates back to the early 1900s, with studies about the nuclear fusion reaction in stars.
- Consolidation and strengthening: The first laboratory experiment demonstrating nuclear fusion in 1934 kickstarted the nuclear fusion movement, which exploded in the 1950s following the construction of the world’s first nuclear fusion reactor in 1958.
- Mainstreaming: Nuclear fusion has yet to establish itself as a part of the mainstream energy industry, with the focus still remaining heavily on research and development. The establishment of the International Atomic Energy Agency (IAEA), the International Energy Agency (IEA), the World Nuclear Association (WNA), the International Thermonuclear Experimental Reactor (ITER) Agreement, and the Fusion Industry Association (FIA) have helped to advance the nuclear fusion market.
| Nuclear Fusion Milestones | Historical Event |
| Initial start | The early history of nuclear fusion dates back to the early 1900s, with studies about the nuclear fusion reaction that naturally occurs in stars. |
| Milestones in nuclear fusion development | 1929: Arthur Eddington first articulated the idea of nuclear fusion. 1934: Ernest Rutherford fused deuterium into helium, producing a blast of energy. 1934: Mark Oliphant demonstrated nuclear fusion in a laboratory setting and discovered helium-3 and tritium. 1939: Hans Bethe and Subrahmanyan Chandrasekhar figured out the precise subatomic process of fusion. 1950s: Andrei Sakharov and Igor Tamm conceptualized the tokamak, which would become the preferred fusion reactor today. 1951: Lyman Spitzer invented the stellarator, another type of fusion reactor. 1958: The Atoms for Peace conference opened the door to researching nuclear fusion for energy purposes. 1958: The world’s first tokamak fusion reactor, the T-1, was constructed in Russia. 1983: The Joint European Torus (JET) tokamak was constructed, the largest operational nuclear fusion reactor to achieve nuclear fusion at the time. 1991: JET achieved the world’s first controlled release of fusion power. 2006: The International Thermonuclear Experimental Reactor (ITER) agreement was signed. 2021: The world record fusion power, 59 megajoules of energy, was achieved in The Joint European Torus (JET) tokamak fusion reactor. 2022: The National Ignition Facility at Lawrence Livermore National Laboratory in California (US) demonstrated the viability of nuclear fusion energy for the first time. 2023: The Joint European Torus (JET) tokamak began the decommissioning process. 2023: The National Ignition Facility at Lawrence Livermore National Laboratory replicated the ignition process three more times. 2024: German startup Proxima Fusion revealed an open-source design for the world’s first, commercial nuclear fusion plant based on the Stellarator model. 2025: The WEST tokamak set a new record by maintaining a hot fusion plasma for 22 minutes at a temperature of 50 million °C (122 million °F). 2025: The EAST tokamak set a new record by maintaining a steady fusion reaction for 1,066 seconds. |
| Current status | Currently, nuclear fusion does not supply energy to the power grid. The focus remains on refining the technology and increasing investments. There are currently more than 10 stellarators and 60 tokamaks in operation worldwide, but none produce electricity. |
| Future outlook | The future of nuclear fusion will depend on us overcoming the two main challenges to nuclear fusion: maintaining the reaction and generating more energy from the reaction than was required to start the reaction. This will require increased funding and further technological advancements. |
| Key policy developments | 1957: International Atomic Energy Agency (IAEA) 1974: International Energy Agency (IEA) 1994: Nuclear Energy Institute (NEI) 1998: World Nuclear Transport Institute (WNTI) 2001: World Nuclear Association (WNA) 2006: The International Thermonuclear Experimental Reactor (ITER) Agreement and ITER Project 2015: Paris Climate Agreement 2018: The Fusion Industry Association (FIA) |
When and How Did Nuclear Fusion Get Started
Radioactivity has always been present on Earth, but it wasn’t seriously studied until the late 1800s. And it wasn’t until 1920 that the concept of nuclear fusion was even realized.
1920: British astrophysicist Arthur Eddington theorized that stars get their energy from the fusion of hydrogen into helium. His theory laid the foundation of modern theoretical astrophysics.
1929: British and Dutch physicists Robert d’Escourt Atkinson and Fritz Houtermans suggested that fusing nuclei together could produce large amounts of energy. They also calculated the rate of nuclear fusion in stars.
How Has Nuclear Fusion Developed Over Time
Nuclear fusion development exploded in the 1950s following the invention of the first nuclear fusion reactors. Pending more research and development, nuclear fusion could play an important role in the long-term global energy transformation.
What Are Milestones in Nuclear Fusion Development
The first laboratory experiment demonstrating nuclear fusion kickstarted the nuclear fusion movement, which saw rapid growth beginning in the 1950s.
1934: Ernest Rutherford fused deuterium into helium and observed an “enormous effect”, a release of energy. This would pave the way for modern nuclear fusion research.
1934: Australian physicist Mark Oliphant became the first to demonstrate nuclear fusion in a laboratory setting. He also discovered helium-3 and tritium, both of which are used in nuclear fusion, and the fusion reaction which formed the basis for a hydrogen bomb.
1939: German and Indian physicists Hans Bethe and Subrahmanyan Chandrasekhar demonstrated that stars are fueled by nuclear fusion. They identified the “proton-proton chain”, which is the process that enables stars to generate energy and the model for modern fusion.
1950s: Soviet scientists Andrei Sakharov and Igor Tamm conceptualized the tokamak, which, like the stellarator, used magnetic fields to control plasma particles and maintain the right conditions for fusion reactions to occur. Tokamaks are the preferred option today for nuclear fusion energy power plants because they are easier to build than stellarators and are better at keeping plasmas hot.
1951: Lyman Spitzer invented the stellarator, a machine that uses magnetic fields to control plasma particles and maintain the right conditions for fusion reactions to occur. This was the first model for harnessing fusion reactions.
1958: Nuclear fusion research was declassified at the Atoms for Peace conference in Geneva, which opened the door to researching fusion for energy purposes. Previously, nuclear fusion research was linked only to atomic weapons development.
1958: The world’s first tokamak fusion reactor, the T-1, was constructed in Russia.
1983: The Joint European Torus (JET), the largest operational nuclear fusion reactor to achieve nuclear fusion at the time, was constructed.
1991: JET achieved the world’s first controlled release of fusion power. Previously, fusion reactions had only taken place uncontrollably via hydrogen bombs.
2006: The International Thermonuclear Experimental Reactor (ITER) agreement was signed, and the ITER project was formed. ITER is both an international cooperation between 35 countries and the name of what will be the world’s largest and most advanced tokamak reactor.
2021: The world record fusion power was achieved in The Joint European Torus (JET) tokamak. JET produced 59 megajoules of energy, double the previous record amount. It was also the first reactor to run off of a 50-50 mix of tritium and deuterium.
2022: The National Ignition Facility at Lawrence Livermore National Laboratory in California (US) demonstrated the viability of nuclear fusion energy for the first time ever when a fusion reaction produced more energy than was needed to spark the reaction. The machine’s laser fired 2 megajoules onto a target and produced 3 megajoules of energy.
2023: The Joint European Torus (JET) tokamak began the decommissioning process, ending 40 years of history making experiments.
2023: The National Ignition Facility at Lawrence Livermore National Laboratory replicated the ignition process three more times, further proving the viability of nuclear fusion.
2024: German startup Proxima Fusion revealed an open-source design for the world’s first, commercial nuclear fusion plant based on the Stellarator model. The model is slated to be complete by 2027, the pilot plant (Alpha) by 2031, and commercialization sometime in the 2030s.
2025: The WEST tokamak, a fusion research device located in France, set a new record by maintaining a hot fusion plasma for 22 minutes at a temperature of 50 million °C (122 million °F). Keeping plasma stable is necessary to make fusion a viable, long-term energy source.
2025: The EAST tokamak, a fusion research device located in China, set a new record by maintaining a steady fusion reaction for 1,066 seconds (17.7 minutes).
How Has the Nuclear Fusion Market Developed Recently
Nuclear fusion currently does not currently supply energy to the power grid. The focus remains on refining the technology and increasing investments.
What Is the Present Status of Nuclear Fusion
In terms of installed capacity, there are currently more than 10 stellarators and 50 tokamaks in operation worldwide, but there are currently no operating reactors that provide energy to our power grid.
As part of The International Thermonuclear Experimental Reactor (ITER) agreement, the world’s largest tokamak, also named ITER, is currently being built in France. Weighing 23,00 tons, the machine will be able to maintain a temperature 10x that of the sun’s core and will have a 500 MW fusion energy output power once constructed. Although it will not be used to generate electricity, the technology of ITER will set the standard for future reactors.
In terms of funding, nuclear fusion investments grew to over $7.1 billion in 2024. Most notably, the amount of public investment into private companies grew from $271 million in 2023 to $426 million in 2024, indicating a heightened interest in commercializing nuclear fusion sooner rather than later.
Fusion has faced an uphill battle partly because of the nature of fusion reactions. Presently, the two main challenges to nuclear fusion are maintaining the reaction and generating more energy from the reaction than was required to start the reaction.
Nuclear fusion experiments themselves are relatively easy to achieve; however, the reaction typically only lasts a fraction of a second. The main challenge with nuclear fusion comes with sustaining fusion reactions for prolonged periods of time. To keep a nuclear fusion reaction going, hydrogen isotopes must be confined and maintained at extremely high pressures and temperatures that are several times hotter than the sun.
In terms of recent breakthroughs:
- In 2023, The National Ignition Facility at Lawrence Livermore National Laboratory built upon their 2022 breakthrough by replicating the ignition process three more times, creating more energy from the reaction than was used to initiate the reaction.
- In 2025, The EAST tokamak, a fusion research device located in China, set a new record by maintaining a steady fusion reaction for 1,066 seconds (17.7 minutes).
How Will the Future of Nuclear Fusion Look Like
Nuclear fusion offers the prospect of an inexhaustible energy source for future generations, but it has been held back thus far by unresolved engineering challenges. Achieving fusion energy commercialization will require increased funding and research.
How Nuclear Fusion Will Likely Develop in the Future
Most experts agree that we are unlikely to achieve large-scale nuclear fusion energy generation before 2050. This means that fusion is not an option for meeting the short-term climate goals laid out in The Paris Climate Agreement, which aims to limit global warming to below 2 degrees Celsius (C).
But that doesn’t mean we should give up on nuclear fusion. Nuclear fusion can become a commercially viable energy source if we develop a steady and reliable way of maintaining the fusion reaction.
In order to achieve commercial energy generation, we must overcome the two main challenges to nuclear fusion: maintaining the reaction and generating more energy from the reaction than was required to start the reaction. This will require increased funding and further technological advancements.
What Policies Are Put in Place to Support Nuclear Fusion Usage
The most well-known piece of legally binding, international climate mitigation legislation is The Paris Agreement, the goal of which is to limit global warming to below 2 degrees Celsius (C), preferably to 1.5C, compared to pre-industrial levels.
The Paris Agreement specifically notes a transition towards clean energies, such as nuclear energy, as being a critical part of meeting these goals.
Check out the highlights of the 2015 COP21 directly from the UN Climate Change channel:
In addition, The International Energy Agency’s (IEA) Net Zero Emissions by 2050 Scenario is one framework for the global energy sector to achieve net zero CO2 emissions by 2050 and universal energy access by 2030.
There are many global and country-specific nuclear policies and organizations aimed at meeting the 2050 net zero scenario, including:
- 1957 – International Atomic Energy Agency (IAEA): The IAEA was founded as fears about nuclear technology began to develop. It is an organization within the United Nations that seeks to promote the safe, secure, and peaceful use of nuclear technologies through international cooperation.
- 1974 – The International Energy Agency (IEA): The IEA was founded in response to the major oil disruptions in 1974. It promotes international energy cooperation, including nuclear energy, and is made up of 31 member countries.
- 1994 – Nuclear Energy Institute (NEI): The NEI was founded as the policy organization of the nuclear energy industry. They seek to promote the global growth of nuclear energy through effective policies.
- 1998 – World Nuclear Transport Institute (WNTI): The WNTI was founded to represent the collective interests of the nuclear transport industry. They aim to ensure safety and security in the global transport of nuclear materials.
- 2001 – World Nuclear Association (WNA): The WNA was established as the leading international organization to represent the global nuclear industry.
- 2006 – The ITER Agreement: ITER is a global scientific partnership established as a collaborative international project to develop fusion energy for peaceful purposes. Upon construction, the ITER tokamak will be the largest magnetic confinement fusion experiment in the world.
- 2018 – The Fusion Industry Association (FIA): The FIA was formed to be the voice of the private fusion industry. They are a nonprofit organization comprised of private companies striving to make nuclear fusion commercially viable.
If you are interested in learning more about country-specific nuclear energy (both fission and fusion) policies, you can visit the IEA’s nuclear power policy database.
What Are Currently the Different Types of Nuclear Energy
In general, nuclear energy is generated when neutrons either fuse or divide, which releases heat, produces steam, spins a turbine, and drives generators to produce electricity. The two ways we can generate nuclear energy are via nuclear fission or nuclear fusion.
Nuclear Fission Is How We Currently Produce Nuclear Energy
Nuclear fission is the process by which neutrons are used to split the nucleus of an atom, which releases an enormous amount of energy in the form of heat and radiation.
Uranium-235 (U-235) is the isotope of Uranium used in nuclear fission because its atoms are easily split apart in nuclear reactors. Each time the reaction occurs, more neutrons are free to strike more and more nuclei, causing a chain reaction.
All nuclear fission power plants operate in the following manner:
- The reactor starts and U-235 atoms in the reactor core split (fission), releasing heat and neutrons.
- Neutrons fission other nuclei in the reactor core in a chain reaction, generating more heat and more neutrons.
- Control rods contain materials that absorb some of the neutrons, helping to contain the chain reaction.
- The heat generated turns water that surrounds the immersed reactor into steam.
- The steam spins a turbine which drives a generator to produce electricity.
Nuclear Fusion Is Still in the Research and Development Phase
Nuclear fusion is the process by which lighter atoms are combined or fused to create larger and heavier atoms. The sun and stars get their energy from nuclear fusion, as hydrogen atoms fuse together to form helium and matter converts into energy.
Fusion reactions take place inside fusion reactors in plasma, a hot, charged gas made of positive ions and free-moving electrons. Deuterium and tritium, isotopes of hydrogen with extra neutrons, are the most commonly used nuclear fusion materials.
The two most common fusion reactors in use today are tokamaks and stellarators. Both use magnetic fields to confine plasma in the shape of a donut.
- Tokamaks: Induce electric currents inside of the plasma. Tokamaks are easier to build than stellarators and are better at keeping plasmas hot. They are the preferred option today for nuclear fusion energy power plants.
- Stellarators: Use external coils to generate a twisting magnetic field. They require less injected power, have greater design flexibility, and are better at keeping plasma stable than tokamaks. However, they are also more complex to build.
Nuclear fusion is very hard to control within a laboratory setting; therefore, nuclear fusion is still very much in the research and development phase. More still needs to be done to determine if it could be another viable energy source.
Final Thoughts
The early history of nuclear fusion dates back to the early 1900s, with studies about the nuclear fusion reaction that naturally occurs in stars. When Mark Oliphant demonstrated nuclear fusion in a laboratory setting, he kickstarted the nuclear fusion movement. The invention of the stellarator and tokamak fusion reactors in the 1950s spurred further research into fusion’s commercial viability.
Currently, nuclear fusion does not supply energy to our power grid. The focus remains on refining the technology and increasing investments. There are currently more than 10 stellarators and 50 tokamaks in operation worldwide, but none produce electricity.
Most experts agree that we are unlikely to achieve large-scale nuclear fusion energy generation before 2050. The future of nuclear fusion will depend on us overcoming the two main challenges to nuclear fusion: maintaining the reaction and generating more energy from the reaction than was required to start the reaction. This will require increased funding and further technological advancements.
Stay impactful,
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