Nuclear fusion

Atomic energy can be released in two ways – either by breaking up heavy nuclei, like uranium, into smaller fragments, releasing a lot of energy in the process, or by fusing together light nuclei like hydrogen to form heavier stable nuclei and high-energy neutrons which carry a lot of energy that can be harnessed.
The former process is nuclear fission, and it is what happens in established nuclear reactors around the world.
The second route is nuclear fusion, and this is the way stars generate energy. In Sun, for example, hydrogen is being converted into helium, releasing huge amounts of energy.

It is a nuclear process, where energy is produced by smashing together light atoms. It is the opposite reaction of fission, where heavy isotopes are split apart.
Fusion is the process by which the sun and other stars generate light and heat.
In a fusion reaction, two light nuclei merge to form a single heavier nucleus. The process releases energy because the total mass of the resulting single nucleus is less than the mass of the two original nuclei.
The leftover mass becomes energy. Einstein’s equation (E=mc2), which says in part that mass and energy can be converted into each other, explains why this process occurs.
It’s most easily achieved on Earth by combining two isotopes of hydrogen: deuterium and tritium.
Nuclear fusion is a clean and green route to producing energy, as it does not involve any remnant radioactive waste products.
Fusion reactions power hydrogen bombs.

An experiment at the U.S. National Ignition Facility (NIF), has come close to demonstrating the nuclear fusion energy in its lab.

So far, fusion devices that show a net energy gain have not been demonstrated in labs. This is the first time, a lab has come close to demonstrating a nuclear energy fusion

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