Basic Explanation of Nuclear Fusion

Fusion means to combine several things together in one thing. The nuclear fusion is combining smaller atomic nuclei into larger ones. Naturally this reaction occurs in the core of a star and this reaction occurs in hydrogen bombs, fusion reactors. The Sun is fusing hydrogen into helium nuclei. The Sun has composition of approximately 72% of hydrogen and 27% of helium. The energy released in many fusion reactions is much greater than amount of energy released in fission reaction.

The Sun is powered by fusion reaction. This reaction involves nuclei isotopes of hydrogen and helium. This reaction starts when two atoms of hydrogen accelerated by the sun’s huge high temperature and high pressures combined to create an atom of deuterium an isotope of hydrogen. The fusion reaction releases a positron and heat energy.
After that another hydrogen atom joins to the deuterium to form helium-3. This reaction releases a lot of energy too in the form of gamma radiation.
Then two atoms of helium-3 combine together to form an atom of helium-4 and 2 hydrogen atoms, these 2 hydrogen atoms can be used to start reaction again. The final step release huge amount of energy in the form of gamma radiation too.

This reaction requires 6 atoms of hydrogen to input, but it produces only two atoms of hydrogen and the rest is the helium. This is the reason why our Sun is going to run out of hydrogen in approximately 5.5 billion years.

The reactions described above involve only nucleus of atoms because it’s too hot inside the Sun and the hydrogen can’t keep its electrons. It’s just the soup of electrons and protons zipping around separately. This condition of matter is called a Plasma. These protons are ionized hydrogen, it means they have positive electric charges. Two positively charged particles will repell, so to combine two positively charged protons you need to overcome really big force of "Culomb Barrier" and get particles close enough so Strong Forces would hold them together. It's one of the reasons why it's complicated to reproduce fusion reactions on Earth. Fusion reactions can happen when particles collide at very huge speeds, or under very high pressures. The Sun uses its own mass to pressure these protons in its core and the Sun has aroun 15 million Celsius degrees in its core. Scientist heat particles to approximately 100 million Celsius degrees , at these temperatures particles achieve speeds to produce fusion reactions in a lab environment.

If we able to build efficient fusion reactor on Earth then we will solve many energy related problems. These reactors can potentially produce more energy than almost any other type of energy source. It would have no impact on the environment, but this task is very hard and might be unachievable for a long time, because scientists are working for more than 50 years to build industrial fusion reactor already.