JET is a lot more than a doughnut-shaped metal vessel. There is an entire plant comprised of many different systems that work together to create the  superheated moments in the torus.

Myriad systems pump out the air, cool some parts of the experiment, heat others, inject the fuel and control the plasma, and then clean up afterwards, ready to do it all again.

This section gives some details of the many systems that all make the JET experiment work.