Fusion power

Stars make lots of heat.

They do this by joining tiny bits together. This joins two light bits into one heavy bit. When this happens, it lets out energy.

Scientists want to do this on Earth. They use special tools called reactors. These tools use very hot clouds of gas.

This gas is called plasma.

Some tools use magnets to hold the gas. Other tools use big lasers.

Lasers can squeeze the gas very hard.

This heat can make power for us. It is a way to make electricity. We are still learning how to do it well.

Stars make heat through a process called fusion.

In a star, gravity pulls tiny bits called nuclei together. When they get close, they join to make a heavier nucleus. This change lets out a lot of power.

Scientists want to make this power on Earth. They use special machines called fusion reactors.

To make fusion work, we need a hot cloud of gas. This gas is called plasma. We use two types of hydrogen to make it. These are called deuterium and tritium. These bits fuse to make helium and a neutron. This reaction gives off a lot of energy.

There are two main ways to hold the plasma. Some machines use magnetic confinement fusion. This uses magnetic fields to hold the plasma in place.

Other machines use inertial confinement fusion. These use big lasers to squeeze small fuel pellets.

One place in the United States is the National Ignition Facility. It is a place that studies these big ideas.

Fusion power is a way to make electricity using the same energy that powers the stars.

In a star, huge gravity pulls tiny bits called nuclei together until they join. When these light nuclei combine to form a heavier nucleus, they release a lot of energy. Scientists want to build fusion reactors to do this on Earth. These machines could provide a lot of power with very little radioactive waste. They also have lower safety risks than the nuclear fission used in current plants.

To make fusion work, we must create a hot cloud called plasma.

This plasma is made of bare nuclei and free electrons. Scientists often use two types of hydrogen called deuterium and tritium. This is known as DT fusion. When these two fuse, they create a helium nucleus and an energetic neutron. The neutron carries a lot of the energy away. To make this happen, the fuel must be very hot and under high pressure. It also needs to stay confined for a certain amount of time. This balance is called the Lawson criterion.

Researchers have been studying fusion since the 1940s.

In the 1960s, Soviet experiments showed that the tokamak design was a very good way to hold plasma. Since the 1970s, scientists have also developed ways to use high-energy lasers for fusion. Today, there are two main ways to try to control the plasma. One way is magnetic confinement fusion, or MCF. This uses magnetic fields to hold the plasma in place. The other way is inertial confinement fusion, or ICF. This uses lasers to squeeze small fuel pellets very quickly.

There are many big projects working on this science right now.

In the United States, the National Ignition Facility (NIF) is a very important lab. As of 2025, it is the only lab to show a fusion energy gain factor above one. This means it produced more energy from the reaction than the energy used to start it. Another huge project is called ITER, which is located in France. Scientists also use lithium breeding blankets to help make more fuel. These blankets make tritium when they are hit by neutron radiation.

Learning about fusion helps us understand how the universe works.

You can think of a fusion reactor like a tiny, controlled star inside a machine. Just as the Sun uses gravity to squeeze atoms, we use magnets or lasers. This process turns tiny pieces of matter into huge amounts of heat. We can then use that heat to turn a turbine and make electricity. It is a hard job to reach the point where the power pays for the plant. However, finding a way to do this could change how we power our world.

{ "text": "Fusion power is a method for generating electricity by releasing the heat from nuclear fusion reactions.

In this process, two light atomic nuclei combine to form a single, heavier nucleus. This reaction releases a massive amount of energy. Scientists aim to build fusion reactors to harness this power for human use. Such reactors could provide energy with minimal high-level radioactive waste. They also involve lower inherent safety risks than current nuclear fission plants.

\n\nTo understand the mechanism, we must look at the forces inside an atom. Every nucleus contains protons that carry a positive charge. These protons naturally push away from each other due to electrostatic repulsion. To achieve fusion, nuclei must get close enough for the strong nuclear force to take over. This force pulls them together, but it only works over a very short distance. This distance is roughly one femtometer, which is the diameter of a proton. The energy required to overcome the electrical push is called the Coulomb barrier.

\n\nTo overcome this barrier, the fuel must be extremely hot or accelerated. When atoms are heated past their ionization energy, they lose their electrons. This creates a state of matter called plasma. Plasma is a hot cloud of bare nuclei and free electrons. Because the charges are separated, plasma is electrically conducting. This allows scientists to use magnetic fields to control and contain the particles. For nuclei lighter than iron-56, the fusion reaction is exothermic, meaning it releases energy. Hydrogen is the best fuel because it is easy to ionize and yields the most net energy.\n\nResearchers focus on a specific process called DT fusion. This uses two isotopes of hydrogen: deuterium and tritium. When they fuse, they create a helium nucleus and an energetic neutron. To make this successful, scientists follow the Lawson criterion. This rule states that a system must produce more energy than it loses to the environment. Success depends on the \"triple product\": plasma density, temperature, and confinement time.

If the density is low, like in the ITER device, the temperature or time must be higher. If the density is very high, like at the National Ignition Facility, the time can be very short.\n\nThere are two primary methods for achieving these conditions. The first is magnetic confinement fusion, or MCF. These devices use magnetic fields to hold the plasma in place. Early designs included the z-pinch and the magnetic mirror. However, the tokamak design became dominant after Soviet experiments in the 1960s.

The second method is inertial confinement fusion, or ICF. This approach uses high-energy lasers to compress and heat small fuel pellets. This method has been developed primarily since the 1970s.

\n\nHistory shows how much we have learned about these processes. Research on fusion reactors began in the 1940s. Since then, many different designs have been tested. The tokamak became a leading design due to its success in the mid-20th century. In the 1980s, researchers at Lawrence Livermore National Laboratory developed direct energy conversion. This method uses the movement of charged particles to maintain voltage. It has shown an energy capture efficiency of 48 percent. Today, massive international projects like ITER in France continue this work.\n\nCapturing the energy produced is a major technical challenge. In most designs, the DT reaction releases energy via fast-moving neutrons. These neutrons are electrically neutral, so magnets cannot stop them. Instead, they hit a thick \"blanket\" of lithium surrounding the reactor core. This collision heats the blanket, and a fluid carries that heat to a turbine. This process can also \"breed" more fuel. When neutrons hit the lithium, they create more tritium. This is vital because tritium is scarce on Earth and has a half-life of about 12.3 years.

\n\nAchieving a net gain in energy is the ultimate goal. As of 2025, the National Ignition Facility is the only lab to demonstrate a fusion energy gain factor above one. This means the reaction produced more energy than the laser energy used to start it. However, we still need much higher efficiencies to reach engineering breakeven. This is the point where a plant produces enough net electricity for use. We also aim for economic breakeven, where the energy produced pays for the plant's life-cycle costs. Solving these challenges could transform how the world generates power.", "media": [ "File:Sun in X-Ray.png", "File:Binding energy curve - common isotopes.svg", "File:Deuterium-tritium fusion.svg", "File:Fusion Triples 2021.png", "File:W7X-Spulen Plasma blau gelb.jpg", "File:Preamplifier at the National Ignition Facility.jpg", "File:Chart of Fusion Approaches.png" ] }