ITER tokamak blanket. (Credit © ITER Organization, www.iter.org)

The lining of the inner wall of the tokamak vessel that will be in direct contact with the hot plasma. The blanket is usually made of modules (from stainless steel, or copper), on which can be mounted replaceable first-wall panels (made from beryllium, tungsten, molybdenum, or carbon in case of older tokamaks), able to withstand high temperatures. The blanket protects the chamber wall and the magnetic coils from high-energy neutrons. These slowdown in the blanket material and transform their energy into thermal energy. In the ITER tokamak, the blanket will be actively cooled by flowing water. The blanket contains openings for diagnostics, plasma heating and other equipment. In the case of the ITER tokamak, some of the blanket modules are planned to be tritium breeding modules, which will produce the important fuel component tritium through neutron collisions with lithium.