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Nuclear Fusion

Last updated date: 16th May 2024
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Nuclear Fusion - Definition, Formula and Examples


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Fusion is the process in which the sun and the stars get their powers. It is the reaction in which 2 atoms of hydrogen combine, or fuse together, to form an atom of helium. In the method, some of the mass of the hydrogen is converted into energy. The basic fusion reaction to make happen is fusing deuterium such that heavy hydrogen with tritium (or “heavy-heavy hydrogen”) to make helium and a neutron. Deuterium is plentifully available in regular water. Tritium can be produced by combining the fusion neutron with ample of light metal lithium. This fusion has the potential to be a never-ending source of energy.
To make fusion occur, the atoms of hydrogen must be heated to very high temperatures (100 million degrees) so they are ionized such that forming a plasma and have enough energy to fuse, and then be held together such that defined, long enough for fusion to occur. The sun and the stars do this by gravity. More effective procedures on earth are magnetic bonds, where a strong magnetic field holds the ionized atoms together while they are heated by microwaves or other sources of energy, and inertial confinement, where a small pellet of frozen hydrogen is compressed and heated by a powerful energy beam, such as a laser, so quickly that fusion occurs before the atoms can travel apart.

Who cares? Scientists have attempted to perform fusion work on earth for over 40 years. If we are successful, we will have an energy source that is endless. One out of every 6,500 atoms of hydrogen in normal water is deuterium, giving a gallon of normal water the energy content of 300 gallons of gasoline. In addition to this, fusion would be environmentally friendly, producing no combustion outcomes or greenhouse gases. While fusion is a nuclear process, the results of the fusion reaction such that helium and a neutron are not radioactive, and with proper design, a fusion power plant would be passively safe and would give no long-lived radioactive waste. The Design studies determine that electricity from fusion should be about the same cost as present-day sources.


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Radiation is energy that travels as particles or waves and can be naturally happening or man-made. It is all around us in several forms ranging from radio waves to x-rays to cosmic radiation.

We get benefits from this energy and we classify these energies into 2 main types:

Non-ionizing radiation has enough energy to excite atoms, making them move more swiftly. Some examples of non-ionizing sources are microwave ovens, radio transmissions, cell phones, and visible light.

Ionizing radiation has enough energy to alter atoms by eliminating electrons from them, a process known as ionization. Some examples of ionizing sources are X-rays, nuclear power.

Nuclear Basics 

The Atoms are made up of protons and neutrons, collectively called nucleons, that are surrounded by electrons.

Things you need to know:

The atomic number of an element (Z) is the total number of protons in a nucleus. The atomic number determines what the element is.

The mass number of an element (A) is the total number of nucleons in a nucleus. The number of neutrons in a nucleus is said to be A-Z.

The Atoms of an element can contain different numbers of neutrons. These different number forms are known as isotopes. The nucleus of an isotope is said to be a nuclide.

NOTE: Every part of matter in the Universe, as far as we know, they are made up of one or more elements from the Periodic Table. The smallest part of an element in the periodic table that can exist is an atom.

Detecting Non-Ionizing Radiation (NIR)

Since non-ionizing radiation is just low-energy waves of the electromagnetic spectrum like radio waves or microwaves, detection is hard. But, if you can watch Television, listen to your radio, talk on your mobile phone, use Wi-Fi or other Bluetooth technologies, you are surely being exposed to NIR. To estimate the quantity of low-energy waves, you will need an EMF which is an electromagnetic field.

Detecting Ionizing Radiation

These can be estimated very accurately and one of the fundamental measuring instruments is the Geiger-Muller counter. This instrument to detect the radiation counts the number of radioactive particles which is entering a sensitive detection chamber and translates that signal into a needle movement on an analog dial or value is represented on a screen.

Ask we have already covered all the basic required to understand the concept better. Now let us study what is Nuclear Fusion?

Nuclear Fusion:

It is a nuclear process, where the energy is generated by smashing together light atoms. It is the contrary reaction of fission, where heavy isotopes are split apart. Fusion is the means by which the sun and other stars generate light and heat.
This is most simply achieved on Earth by combining two isotopes of hydrogen such that the deuterium and tritium. Hydrogen is the lightest of all the elements in the periodic element, which is made up of a single proton and an electron. Deuterium has an additional neutron in its nucleus; it can replace one of the hydrogen atoms in water to make what is called heavy water. Tritium has two additional neutrons, and is, hence, 3 times as heavy as hydrogen. In a fusion cycle, tritium and deuterium are combined and appear in the formation of helium, the next heaviest element in the Periodic Table, and the gives out a free neutron.

Deuterium is seen in one part per 6,500 in common seawater, and is hence globally available, eliminating the problem of uneven geographical distribution of fuel resources. This indicates that there will be fuel for fusion if there is water on the planet.

Fusion Power:

Let us understand a fusion reaction. We know that as deuterium and tritium fuse together, their component parts are recombined to form helium atom and a fast neutron. As the 2 heavy isotopes are reassembled into a helium atom, you have additional mass leftover which is then converted into the kinetic energy (KE) of the neutron, according to the very famous Einstein’s formula:

For a nuclear fusion reaction to happen, it is important to bring two nuclei so close that their nuclear forces become active and join the nuclei together. Nuclear forces are small distance forces and must act against the electrostatic forces where the positively charged nuclei repel from each other. This is the reason nuclear fusion reactions occur mostly in very high density and high-temperature environment. 

At very high temperatures, electrons are stripped away from atomic nuclei to form a plasma such that an ionized gas. Under such conditions, the positively charged nuclei that have repulsive electrostatic forces are kept apart, and the nuclei of select light elements can be taken together to fuse and form other elements. Nuclear fusion of light elements gives out vast amounts of energy and is the fundamental energy-producing process in stars.

Answer the following questions:

  • 1. Define the term radiation and explain its types?

  • 2. Define the term Fusion?

  • 3. List the devices used to measure the radiation?

  • 4. Explain the term nuclear fusion with an example?

  • Fill in the blanks:

  • 1. Einstein’s Energy formula is given by ___________. ( Ans: E=mc2 )

  • 2. Deuterium has an additional neutron in its nucleus; it can replace one of the ________ atoms in water to make and this is called_________ ( Ans: Hydrogen, heavy water )

  • 3. __________ is the lightest of all the elements in the periodic element (Ans: Hydrogen)