Nuclear fusion reactions are those that take place inside stars, such as ours. sun, in which two smaller atomic nuclei unite to give rise to a larger, more atomic nucleus. stable. Below we have a mechanism for this type of reaction that occurs in the Sun, between hydrogens, giving rise to helium:
Possible hydrogen fusion reaction taking place on the Sun
But the most important aspect of this type of nuclear reaction is the amount of energy released. To get an idea, the fusion of only 2. 10-9% of deuterium (hydrogen with a neutron and a proton in the nucleus)would supply an amount of energy that would be enough to sustain the entire world's energy demand for a year!
That's why the dream of many scientists is to be able to harness the energy released in fusion reactions. The reactors currently used in nuclear power plants are nuclear fission, which is the anti-fusion process and which produces a smaller amount of energy.
Uncontrolled fusion has already been used in hydrogen bomb or thermonuclear
, in the year 1952, launched by the United States on an atoll in the Pacific. This bomb was dubbed the “Mike” and had 700 times the power of the Hiroshima bomb.In addition to the large amount of energy released, others benefits of using nuclear fusion to generate energy are that the materials used in these reactions are easily obtainable., for deuterium is found in water molecules, tritium (hydrogen isotope that has a proton and two neutrons in the nucleus) can be obtained from lithium, and lithium is a naturally occurring metal.
Another factor is that, unlike nuclear fission, the fusion products are not radioactive and are therefore considered a “clean” type of energy that does not cause changes in the environment.
But to be used to generate energy, it must be a controlled reaction and for that there are still some hindrances:
For the fusion to be effective, high temperatures are needed, as in the Sun, which has regions with temperatures in the order of 100 million degrees Celsius! This large amount of energy is needed to overcome the repulsion force arising from the positive charges of the nuclei that will unite.
Currently, this is achieved through the energy released in the controlled fission reaction of an atomic bomb, which serves as a trigger for the nuclear fusion reaction.
Another problem that arises is: how to work in a controlled manner with materials at thousands of degrees Celsius? What materials could be used to build the reactor that would withstand such high temperatures?
There is also a need for a rapid flow of energy released in the fusion reaction.
Research in this area has led to a type of reactor called Tokamak, which is used today only for research. The most famous is the one in Princeton, United States, which works at a temperature of 100 million degrees Celsius. Below is the Tokamak COMPASS at the IPP presented in Prague, Czech Republic, during the Week of Science and Technology organized by the Academy of Sciences of the Czech Republic on November 2, 2012:
Tokamak COMPASS at IPP presented in Prague[2]
In these reactors an extremely strong magnetic field is produced. Deuterium and tritium gases are injected and heated to thousands of degrees Celsius to react. Since there is the passage of electric current and the generation of strong magnetic fields, a plasma is formed, which is in a tube inside the reactor, not coming into contact with its walls.
The above stamp, printed in the USSR, shows a tokamak thermonuclear fusion device circa 1987[3]
However, to date, a means of obtaining useful energy from such a reactor has not yet been discovered. the energy spent to activate the magnetic field where the plasma is confined is still greater than the energy obtained from the fusion inside the reactor.
* Image credits:
[1] Author: Mike Garrett/Wikimedia Commons
[2] Nataliya Hour/ Shutterstock.com
[3] Jim Pruitt/Shutterstock.com
By Jennifer Fogaça
Graduated in Chemistry
Source: Brazil School - https://brasilescola.uol.com.br/quimica/reator-fusao-nuclear.htm