A fusion reactor is essentially a magnetic bottle containing the same processes that occur in the sun. Deuterium and tritium fuels fuse to form a vapor of helium ions, neutrons and heat. As this hot, ionized gas—called plasma—burns, that heat is transferred to water to make steam to turn turbines that generate electricity. The superheated plasma poses a constant threat to the reactor wall and the divertor (which removes waste from the operating reactor to keep the plasma hot enough to burn).