Containing a substance at 100 million degrees.

We have talked about fusion energy, the fusion industry and the importance of fusion. In our discussion we referred to the various fusion reactor designs. Today we will say a bit about how one goes about containing fusion reactions and this will set the stage to talk about these designs.

As we have previously mentioned, one key ingredient to achieve fusion is very high temperatures, much higher even than the centre of the sun. At these temperatures, the molecules and atoms that make up the substance we want to heat up completely dissociate and become ionised. This means that the nuclei and the electrons separate, so that we have a “soup” of positive ions and negative electrons; our substance is thus made of charged particles. This is a state of matter we don’t learn about in school and is called a “plasma” (so we have solid, liquid, gas and plasma, the fourth state of matter).

How does one contain a substance at such high temperature? Thankfully, nature gives us a helping hand; charged particles follow magnetic field lines. This means that, if we have circular magnetic field lines (think of a donut shape), the particles will travel around in a circle, and will thus be contained!

In magnetic confinement fusion, therefore, we use magnetic field lines to contain the plasma (there are two other types of confinement, which we can briefly talk about in subsequent posts).

As a final note to today’s post, we need to highlight that the above is a simplified picture; the details we have glossed over are why our magnetic bottles tend to be quite leaky! The amount of leakage is what a good design aims to limit. More on that in subsequent posts!

Please continue spreading the word about Fusion Reactors.