Tokamak

A tokamak is a big machine.

It looks like a giant ring. It uses strong magnets to hold hot gas. This gas is called plasma.

The magnets make a field. This field keeps the hot gas in place. The gas moves in a circle. It does not touch the walls.

Scientists use this to make power. This power comes from heat. It is a way to make energy.

Many lands build these machines. One big project is in France. It is called ITER.

These machines help us learn about the sun.

A tokamak is a machine used to make power. It works by using a process called fusion. This is the same way the sun makes energy.

To make fusion, we need a very hot gas. This gas is called plasma. Plasma is special because it can move with magnets. A tokamak is shaped like a big donut. This shape is called a torus.

Inside the machine, magnets create a magnetic field. This field acts like an invisible container. It keeps the plasma in a ring shape. The magnets must be very strong. They stop the hot plasma from touching the walls.

Scientists use many ways to heat the plasma. They might use beams of particles or waves. This makes the atoms move very fast. When they hit each other, they fuse. This lets out heat that we can use.

Many countries work on this today. A huge project is called ITER. It is being built in France. It aims to be finished by 2034.

A tokamak is a special machine built to study fusion power. Fusion is the way stars make energy. Scientists want to use this process to make power for people on Earth.

To do this, they must hold a very hot gas called plasma. Plasma is a state of matter where electrons and nuclei move freely. Because it is conductive, magnets can control it. The tokamak uses magnets to keep the plasma in a donut shape. This shape is called a torus.

Making fusion requires many careful steps. First, the machine must create a ring of plasma. It uses a central solenoid and other magnets to shape the ring. These magnets create a magnetic field that acts like an invisible container. This field must be twisted into a helix shape to stay stable. Without this twist, the plasma would drift away and hit the walls.

Next, the plasma must be heated to extreme temperatures. Scientists use methods like neutral-beam injection or special waves to heat it. This makes the atoms move fast enough to collide and fuse. Finally, neutron detectors can measure if the fusion is happening.

The idea for the tokamak began in the Soviet Union. Physicists Andrei Sakharov and Igor Tamm first thought of the concept. They worked on it after reading a letter from Oleg Lavrentiev. Lavrentiev had suggested using magnetic fields to hold hot plasma. In 1951, researchers at the Kurchatov Institute began building these machines. A device called the T-1 was built in 1958. Later, a machine called the T-3 showed very high performance. This led to a "tokamak stampede" as scientists everywhere wanted to build them.

Many famous machines have helped us learn about fusion. The Joint European Torus, or JET, set several big records. It reached a total energy output of 69 MJ. It also hit a fusion power of 16 MW. In the United States, the Princeton Large Torus was a major center for research. Today, the JT-60SA in Japan is the largest operational tokamak by radius. There are also important experiments in China called EAST and in France called WEST.

Building a machine that works like the sun is a huge job. It is so big that one country cannot do it alone. This is why many nations are working on the ITER project. ITER is a massive tokamak being built in Cadarache, France. Construction began in 2013, and assembly started in 2020. The goal is to finish the project by 2034. This project helps us understand how to create clean energy for the future. It brings the whole world together to solve a hard problem.

A tokamak is a sophisticated machine designed to study controlled thermonuclear fusion. This process is the same method stars use to generate immense energy. Scientists aim to replicate this reaction on Earth to produce clean power. To achieve this, the machine must contain a substance called plasma. Plasma is a state of matter where electrons and nuclei are dissociated. Because plasma is electrically conductive, it can be manipulated using magnetic fields.

The tokamak functions by confining plasma within an axially symmetrical torus, which is a donut shape. This confinement is achieved through a complex combination of magnetic fields. A central solenoid and various toroidal and poloidal magnets work together to shape the plasma ring. The magnetic field lines must wind around the torus in a helix shape to maintain stability. Without this helical twist, the plasma would experience drifts and hit the machine walls. Modern tokamaks typically sustain these plasma discharges for durations of seconds or minutes.

Heating the plasma is a critical step in reaching fusion temperatures. For fusion to occur, the fuel must be raised to extreme, thermonuclear temperatures. This ensures that atoms collide at high enough speeds to fuse. Scientists use several specific methods to provide this heat. These include neutral-beam injection and electron or ion cyclotron resonance. Lower hybrid resonance is another method used to energize the plasma. Once the reaction occurs, neutron detectors are used to measure the fusion success.

The concept of the tokamak originated in the Soviet Union. Physicists Andrei Sakharov and Igor Tamm first developed the idea. Their work was influenced by a letter from Oleg Lavrentiev. Lavrentiev had proposed using magnetic fields to contain hot plasma. In 1951, research began at the Kurchatov Institute in Moscow. The T-1 device, built in 1958, is often considered the first tokamak. Later, the T-3 tokamak demonstrated high performance, which triggered a "tokamak stampede" among global scientists.

Research has led to several significant milestones and specialized machine designs. The Joint European Torus, or JET, was a major experimental facility. JET was among the first to run experiments using an admixture of deuterium and tritium. This machine set several records, including a total energy output of 69 MJ. It also reached a fusion power of 16 MW and an energy gain factor (Q) of 0.67. Other notable designs include the spherical tokamak, which investigates different performance parameters.

Today, various large-scale tokamaks serve as the world's primary research tools. The JT-60SA in Japan is currently the largest operational tokamak by radius and plasma current. Other significant operational experiments include WEST in France and EAST in China. In the United States, the Princeton Plasma Physics Laboratory became a major center starting with the 1975 Princeton Large Torus. Even private companies are now involved, such as Commonwealth Fusion Systems with their SPARC design. These machines continue to refine our understanding of plasma stability and heat.

The most ambitious scientific effort is the International Thermonuclear Experimental Reactor, known as ITER. Because the required machines are so large and expensive, no single country can build them alone. ITER is a massive global collaboration currently under construction in Cadarache, France. Assembly of the tokamak began in 2020, and the project aims for completion by 2034.

This project represents the ultimate step in researching whether fusion can provide a steady source of power for the world.