Nuclear Fusion and Stellar Energy

Nuclear Fusion and Stellar Energy:

Nuclear Fusion:

Nuclear Fusion is defined as the process in which two lighter nuclei combine together to form a heavier and stable nucleus, with the release of a large amount of energy.

Since the mass of a single nucleus formed is less than the sum of the masses of nuclei fused, the mass defect is converted into energy. Hence during the fusion process, a large amount of energy is released.

But the problem is how to fuse two nuclei because they would repel each other. For fusion, the parent nuclei must be within a distance of 10^-15 m. They should be imparted high energies to overcome their repulsive forces. This is only possible at very high temperatures that are possible on the sun.

Therefore, fusion is also called a thermonuclear reaction. Artificially such a high temperature (about 10⁷ °C) could be produced using an atom bomb. Thus the explosion of an atom bomb can initiate nuclear fusion.

Stellar Energy:

It is the energy produced in the sun or other stars. Through thermonuclear reactions, large energy is released in which hydrogen is continuously converted into helium. According to Bethe by following two ways fusion takes place-

• Proton-Proton Cycle.
• Carbon-Nitrogen Cycle.

Proton-Proton Cycle:

Different reactions involved in the cycle are as follows-

• Two protons fuse to form deuteron.

• Deuteron combines with another proton to yield He-3.

• Two light He-nuclei fuses to form He-4.

OR

Thus the overall process is written as-

The total energy released is about 26.7 MeV (27 approximately).

Carbon-Nitrogen Cycle:

Here carbon acts as a nuclear catalyst and the different reactions involved are as follows-

The total energy released is about 26.7 MeV (27 approximately).