Ignition criteria for a fusion Deuterium-Tritium plasma on account of fuel dilution by helium ash

Nuclear fusion is the process in which two nuclei of light atoms merge together and free a certain quantity of energy under the form of kinetik energy of the reaction products. These processes play a major role in stars where it is the energy spread by fusion reactions that contrasts the gravitational collapse and keeps the star in equilibrium. Thus, since the second half of the last century, scientists have begun to show interest in nuclear fusion as a possible source of energy exploitable for civil aims. The issue is to reproduce on Earth what does occur in the interior of stars, in a controlled way, that is realizing controlled thermonuclear fusion. How? To date two major approaches have been proposed: inertial confinement approach and magnetic confinement approach. In this work, we will treat a particular topic related to the most important device for magnetic confinement fusion, the tokamak. For fusion reactions to take place, the nuclei have to overcome the potential barrier, called Coulombic barrier, due to the repulsive electric force between them. One way to give them this energy consists in heating them at such a temperature that the thermal energy they have is enough to overcome the Coulombic barrier.