What is Nuclear Fusion?

Nuclear fusion is a process, by which the combination or fusion of two nuclei results in the formation of a heavier nucleus, accompanied by a large-scale change in energy. A very simple example of fusion reaction is, when nuclei of two hydrogen atoms are brought close to each other, then they undergo fusion and form a helium nucleus.

Fusion is an energy releasing process in the low mass number range. But, it is not so in the high mass number region. It has been observed that fusion of two nuclei, whose mass is less than iron, often release energy. Whereas, fusion of nuclei that have higher mass than iron absorb energy. Any two large nuclei will repel each other very strongly, as they approach each other, due to their high nuclear charges.

The essential precondition required for nuclear fusion to take place is that each of the nucleus should be highly energized, to overcome the very strong mutual repulsion of their positively charged nuclei. This is achieved by raising the temperature of the fuel material to an extremely high point.

To attain such a high temperature, in a short span of time, the fuel is enveloped with uranium, and is allowed to undergo fission (a nuclear reaction, in which heavy nucleus of uranium splits into smaller nuclei, and release a lot of energy) chain reaction.

Thus, the heat generated from this reaction energizes the hydrogen atoms, forces them to undergo fusion, and liberates energy in large magnitude.

Australian physicist Mark Oliphant gave an experimental demonstration of nuclear fusion, for the first time in 1932. Later, the stages of the cycle of fusion that takes place in stars, was explained by famous physicist Hans Bethe.

The exploration for the possible uses of this phenomenon for military purposes, began in early 1940s. On the other hand, the research work for utilizing fusion for civilian use started in the 1950s.

The source of energy in the stars including the sun, is believed to be due to the conversion of hydrogen into helium by fusion process. Intensive research to produce electricity from nuclear fusion, has been going on for many years.

Due to some technical and scientific difficulties, the power generated has not been put into practical use so far. Once we overcome these obstacles, electric power generation will be cheaper, and power crisis would be resolved once and for all.

If a fusion reaction is carried out in an uncontrolled manner, then it will cause a thermonuclear explosion akin to exploding a hydrogen bomb.

The major advantages of nuclear fusion are easy availability of fuel and minimum environmental pollution. The fuels used are mainly deuterium and tritium. The former, which is a heavy isotope of hydrogen, can be obtained from the surface waters on Earth.

The latter is produced from lithium, which is abundant on land, as well as in seawater. As both the fuels are almost inexhaustible, the probability of having a fuel crisis is zero, for thousands of years to come.

As fossil fuels are not being used, there is no possibility of release of chemical combustion products. Likewise, no fusion products are formed, and hence, handling and disposal problems do not arise. So far, scientists have not been able to fully control the fusion processes over a prolonged period of time, and hence, it cannot be used for practical purposes.

The energy released in nuclear fusion is much higher than any chemical reactions. It is possible to use this energy in various ways in the future. But care should be taken that it is sustained in a controlled manner, and is used only for peaceful purposes.