G Norris, Fusion frontier, Aviation Week & Space Technology, 20 October 2014, p 42
In US, Lockheed Martin is developing a compact nuclear fusion reactor that could be small enough to apply to interplanetary spacecraft, commercial ships and possibly to aircraft with unlimited endurance. The gaseous fusion fuel comprising the hydrogen isotopes deuterium (from sea water) and tritium (from lithium) is energised within an evacuated vessel by radio-frequency heating, resulting in a plasma of ions and electrons that is controlled by strong magnetic fields. The ions overcome their mutual repulsion, and fuse to create helium-4, freeing the neutrons to flow through the confining magnetic
fields and so heating the reactor wall. This heat is gathered by conventional heat exchangers, and applied to turbine generators. The system is expected to be operational within ten years.