Fusion

Bringing Together

Fusion is the process of two small atomic nuclei coming together to make a larger nucleus which is stable. The simplest nuclei to use are deuteriumand tritium (isotopes of hydrogen). Scientists find deuterium in the oceans, so it's pretty easy to find if you know where to look. 

Look in the Sky

The fusion reactions in many stars are different from the reactions we are trying to develop on Earth. Scientists call the fusion process on a star theproton-proton chain reaction. Two protons collide with each other and form something called a deuteron. A third proton then collides with the deuteron to create a helium isotope. Helium isotopes then fuse to make beryllium, which then breaks down. When the beryllium breaks down, two protons are released and the reaction can start again. 

Fizz vs. Fuse

When we were kids we always got fusion and fission confused. The confusion wasn't because the processes were similar; the words were just similar. You need to remember that one process is a breaking down process and the other is a process of building up. When things fuse (fusion), you start with smaller objects (tritium, deuterium) and build larger objects (helium). When things "fiss" or break down, you start with a larger object (uranium) and finish with smaller objects (strontium, calcium, barium, etc). 

Making Fusion a Reality

Fusion reactions need very hot environments to occur. Temperatures hit millions of degrees, like the temperature of the Sun. When you heat a gas, you create plasma. The problem is that we can't create a container that can make plasma hot enough to let a fusion reaction occur. To make sure that the plasma doesn't really touch the container, scientists use magnetic fields to hold the plasma in place. It's like the plasma is just floating, not touching anything. Right now the best container is in the shape of a torus. That's like the shape of a doughnut. Compared to a fission reaction, there is very little radioactivity released when a fusion reaction is complete.