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Tokamak: A Look Inside a Nuclear Fusion Reactor

Nuclear Fusion Overview

Nuclear fusion releases energy through the reaction of two lighter atoms fusing together to form one heavier particle. Nuclear fusion releases energy because the nuclear binding energy of the products is greater than that of the reactants. Technically, all atoms with a lower atomic mass than iron can be fused, as iron has the strongest bonding energy per nucleon.

Nuclear fusion on Earth focuses on the fusion of deuterium (a hydrogen atom with one neutron) and tritium (a hydrogen atom with two neutrons. D-T fusion, as it is called, yields an alpha particle (helium atom), a neutron, and energy. The picture below illustrates a single D-T fusion reaction.

The fusion reactor that this project focuses on is called a tokamak, a toroidal-shaped reactor. The deuterium, tritium, fusion products, and other particles circle around the inside of the tokamak as a plasma. The plasma is confined with magnetic fields, as it would otherwise damage the walls. The picture below shows the inside of a tokamak, with a small insert of the inside when plasma is present.

The Project

The purpose of this project is to construct a simple demonstration of the inside of a tokamak in VPython. The program simulates hydrogen atoms as well as larger particles, such as alpha particles still contained in the plasma. Below is a screenshot of the tokamak with the rotating particles.

The magnetic fields used to confine and rotate the plasma also cause it to rotate around its forward trajectory, in something called a Larmor radius. This movement was also simulated, as seen in the screenshot below.

Overall, the program can be used as a supplement to the initial understanding of fusion reactions in a tokamak reactor. Although it does not delve deep into the plasma and fusion science that is present inside a tokamak, much of this information has yet to be understood. Nuclear fusion an exciting field, and the thought of a commercial fusion power plant is quite exciting indeed.