In a production design, the magnets would need to be protected from the 14.1 MeV neutrons being produced by the fusion reactions. This is normally accomplished through the use of a breeding blanket, a layer of material containing large amounts of lithium. In order to capture most of the neutrons, the blanket has to be about 1 to 1.5 meters thick, which moves the magnets away from the plasma and therefore requires them to be more powerful than those on experimental machines where they line the outside of the vacuum chamber directly.