Thermonuclear weapon

A thermonuclear weapon, fusion weapon, or hydrogen bomb (H-bomb) is a second-generation nuclear weapon, using nuclear fusion. The most destructive weapons ever created, their yields typically exceed first-generation nuclear weapons by twenty times, with far lower mass and volume requirements. Characteristics of fusion reactions can make possible the use of non-fissile depleted uranium as the weapon's main fuel, thus allowing more efficient use of scarce fissile material. Its multi-stage design is distinct from the usage of fusion in simpler boosted fission weapons. The first full-scale thermonuclear test (Ivy Mike) was carried out by the United States in 1952, and the concept has since been employed by at least the five NPT-recognized nuclear-weapon states: the United States, Russia, the United Kingdom, China, and France. The design of all thermonuclear weapons is believed to be the Teller–Ulam configuration. This relies on radiation implosion, in which X-rays from detonation of the primary stage, a fission bomb, are channelled to compress a separate fusion secondary stage containing thermonuclear fuel, primarily lithium-6 deuteride. During detonation, neutrons convert lithium-6 to helium-4 plus tritium. The heavy isotopes of hydrogen, deuterium and tritium, then undergo a reaction that releases energy and neutrons. For this reason, thermonuclear weapons are often colloquially called hydrogen bombs or H-bombs. Additionally, most weapons use a natural or depleted uranium tamper and case. This undergoes fast fission from fast fusion neutrons and is the main contribution to the total yield and radioactive fission product fallout. Thermonuclear weapons were thought possible in 1941 and were the subject of basic research during the Manhattan Project. The first Soviet nuclear test triggered an all-out pursuit of a thermonuclear weapon in the US, despite initial opposition by many former Manhattan Project scientists. The Teller-Ulam configuration, named for its chief contributors, Edward Teller and Stanisław Ulam, was outlined in...