Radioactivity and Particles: Nuclear Fusion

Nuclear fusion is the process by which two lighter atoms are combined to create a heavier one; this process releases great quantities of energy.
It is different from nuclear fission, which is a process where a heavy nucleus splits into two lighter ones.
In nuclear fusion, the combined mass of the resulting atom is less than the original masses of the individual atoms. The missing mass is released as energy, following Einstein’s equation E=mc^2, which states energy (E) is equal to mass (m) times the speed of light (c) squared.
Fusion powers the sun and all other stars. The sun’s power mainly comes from the fusion of hydrogen to create helium.
The temperature and pressure conditions for nuclear fusion to take place are extreme, and it’s a challenge to replicate these conditions when trying to tap into fusion as an energy source on Earth.
Fusion is considered an attractive option for power generation as it produces no greenhouse gases or long-lived nuclear waste. The raw materials - hydrogen and its isotopes - are plentiful and widely available.
Deuterium-deuterium fusion and deuterium-tritium fusion are two commonly studied reactions. Deuterium-deuterium fusion is considered an appealing future source of energy because both deuterium and tritium are isotopes of hydrogen, which is abundant on Earth.
Obstacles to generating power from fusion on Earth mainly stem from the difficulties in containing the hot plasma (a state of matter that includes charged particles) required for fusion reactions. This is often attempted with magnetic fields in a device called a tokamak.
At very high temperatures, the ions in a plasma move so fast they can overcome the repulsion between positive charges, collide, and fuse together.
It’s worth noting that while fusion processes can release large amounts of energy, getting more energy out of a fusion reaction than what was put in to start the reaction has proved to be extremely challenging. This is a key hurdle that must be overcome to make fusion a viable energy source.
Fusion reactions are the main process by which elements heavier than hydrogen are created in the universe. This process, called nucleosynthesis, occurs in the cores of stars.