It's a big ring of magnetic coil, superconducting coil, and it makes a magnetic field in a ring like this, and the hot gas in the middle, which is called a plasma, is trapped.
E un inel mare de bobină magnetică, bobină supraconductoare, ce produce un câmp magnetic într-un inel ca acesta, iar gazul fierbinte din mijloc, numit plasmă, e blocat.