Thermonuclear weapon

A thermonuclear weapon, fusion weapon or hydrogen bomb (H-bomb) is a second-generation <a href="/facts/Nuclear_weapon/QVdBcMdm">nuclear weapon</a>, utilizing <a href="/facts/Nuclear_fusion/hP0gLDqj">nuclear fusion</a>. The most destructive weapons ever created, their <a href="/facts/Nuclear_weapon_yield/53of1vqQ">yields</a> typically exceed <a href="/facts/Nuclear_weapon_design/gw0LEc74">first-generation nuclear weapons</a> by twenty times, with far lower mass and volume requirements. Characteristics of fusion reactions can make possible the use of <a href="/facts/Fissionable/XJR9qoxW">non-fissile</a> <a href="/facts/Depleted_uranium/oKGvpUlW">depleted uranium</a> as the weapon's main fuel, thus allowing more efficient use of scarce <a href="/facts/Fissile_material/XJR9qoxW">fissile material</a>. Its multi-stage design is distinct from the usage of fusion in simpler <a href="/facts/Boosted_fission_weapon/U11GQ2mf">boosted fission weapons</a>. The first full-scale thermonuclear test (<a href="/facts/Ivy_Mike/yFqF9H72">Ivy Mike</a>) was carried out by the United States in 1952, and the concept has since been employed by at least the five <a href="/facts/Treaty_on_the_Non-Proliferation_of_Nuclear_Weapons/yE0ekVtm">NPT</a>-recognized <a href="/facts/List_of_states_with_nuclear_weapons/urhNKh4Q">nuclear-weapon states</a>: the <a href="/facts/Nuclear_weapons_of_the_United_States/sBxLkstG">United States</a>, <a href="/facts/Russia_and_nuclear_weapons/eXCHTUhg">Russia</a>, the <a href="/facts/Nuclear_weapons_of_the_United_Kingdom/lK8jPFP1">United Kingdom</a>, <a href="/facts/China_and_nuclear_weapons/SeQ2B1CW">China</a>, and <a href="/facts/France_and_nuclear_weapons/A3KQUha6">France</a>.
The design of all thermonuclear weapons is believed to be the <a href="/facts/History_of_the_Teller%25E2%2580%2593Ulam_design/3D6lqIA7">Teller–Ulam configuration</a>. This relies on <a href="/facts/Radiation_implosion/tAE1y0Qt">radiation implosion</a>, in which <a href="/facts/X-rays/wseP79cN">X-rays</a> from detonation of the primary stage, a <a href="/facts/Fission_bomb/QVdBcMdm">fission bomb</a>, are channelled to compress a separate fusion secondary stage containing thermonuclear fuel, primarily <a href="/facts/Lithium_hydride/uWCl2pST">lithium-6 deuteride</a>. During detonation, neutrons convert <a href="/facts/Lithium-6/XC311sQu">lithium-6</a> to <a href="/facts/Helium-4/vNsL5qhC">helium-4</a> plus <a href="/facts/Tritium/HWSa6EHy">tritium</a>. The heavy <a href="/facts/Isotope/KD9B1y6o">isotopes</a> of hydrogen, <a href="/facts/Deuterium/Bv4wfCkw">deuterium</a> and tritium, then undergo <a href="/facts/Deuterium%25E2%2580%2593tritium_fusion/SDEJ3Nw0">an energetic reaction</a>. For this reason, thermonuclear weapons are often colloquially called hydrogen bombs or H-bombs.
Additionally, most weapons use a <a href="/facts/Natural/mB2x6tF4">natural</a> or <a href="/facts/Depleted_uranium/oKGvpUlW">depleted uranium</a> tamper and case. This undergoes <a href="/facts/Fast_fission/tY0SxzVe">fast fission</a> from <a href="/facts/Fusion_neutron/oRCM1geb">fast fusion neutrons</a> and is the main contribution to the total yield and <a href="/facts/Radioactivity/Ya6FVjt4">radioactive</a> fission product <a href="/facts/Nuclear_fallout/I1kJkLKt">fallout</a>.
Thermonuclear weapons were thought possible since 1941 and received basic research during the <a href="/facts/Manhattan_Project/gtg8yRK2">Manhattan Project</a>. The <a href="/facts/RDS-1/mgXDp8fa">first Soviet nuclear test</a> spurred US thermonuclear research. The Teller-Ulam configuration, named for its chief contributors, <a href="/facts/Edward_Teller/9g3Mr9Mp">Edward Teller</a> and <a href="/facts/Stanis%25C5%2582aw_Ulam/KaJPqENX">Stanisław Ulam</a>, was outlined in 1951, with contribution from <a href="/facts/John_von_Neumann/aUk6urof">John von Neumann</a>. <a href="/facts/Operation_Greenhouse/0hCFWth1">Operation Greenhouse</a> investigated thermonuclear reactions before the full-scale Mike test. 
Multi-stage devices were independently developed and tested by the Soviet Union (<a href="/facts/RDS-37/GFGsMb2W">1955</a>), the United Kingdom (<a href="/facts/Operation_Grapple/LoDVTsXp">1957</a>), China (<a href="/facts/Test_No._6/QXd6CGTL">1966</a>), and France (<a href="/facts/Canopus_(nuclear_test)/CXMu79xC">1968</a>). There is not enough public information to determine whether <a href="/facts/India_and_weapons_of_mass_destruction/IcG8vgjd">India</a>, <a href="/facts/Nuclear_weapons_and_Israel/GQuaIGcb">Israel</a>, or <a href="/facts/North_Korea_and_weapons_of_mass_destruction/1yT71YSy">North Korea</a> possess multi-stage weapons. <a href="/facts/Pakistan_and_weapons_of_mass_destruction/sfNPnK3S">Pakistan</a> is not considered to have developed them. After the 1991 <a href="/facts/Collapse_of_the_Soviet_Union/Fyn5jw3n">collapse of the Soviet Union</a>, Ukraine, Belarus, and Kazakhstan became the first and only countries to relinquish their thermonuclear weapons, although these had never left the operational control of <a href="/facts/Strategic_Rocket_Forces/HMEx2wvU">Russian forces</a>. 

Thermonuclear weapons are the only artificial source of explosions above one <a href="/facts/Megatons_of_TNT/nEQ5z8mp">megaton TNT</a>. The <a href="/facts/Tsar_Bomba/qbjpPwN2">Tsar Bomba</a> was the most powerful bomb ever detonated at 50 megatons TNT. As they are the most efficient design for yields above 50 <a href="/facts/TNT_equivalent/nEQ5z8mp">kilotons of TNT</a> (210 TJ), and with decreased relevance of <a href="/facts/Tactical_nuclear_weapons/z1M5ekhB">tactical nuclear weapons</a>, virtually all nuclear weapons deployed by the five recognized nuclear-weapons states today are thermonuclear. Their development dominated the <a href="/facts/Cold_War/spJdJQ3q">Cold War</a>'s <a href="/facts/Nuclear_arms_race/2IabKwkf">nuclear arms race</a>. Their destructiveness and ability to miniaturize high yields, such as in <a href="/facts/MIRV/cmzWwXxy">MIRV</a> warheads, defines <a href="/facts/Nuclear_deterrence/ImetP5jV">nuclear deterrence</a> and <a href="/facts/Mutual_assured_destruction/ImetP5jV">mutual assured destruction</a>. Extensions of <a href="/facts/Thermonuclear_weapon_design/gw0LEc74">thermonuclear weapon design</a> include <a href="/facts/Clean_bomb/T9zFe3H0">clean bombs</a> with marginal fallout and <a href="/facts/Neutron_bomb/CDQspbMM">neutron bombs</a> with enhanced penetrating radiation. Nonetheless, most thermonuclear weapons designed, including all current US and UK nuclear warheads, derive most of their energy from fast fission, causing high fallout.

Thermonuclear weapon open-in-new

Thermonuclear weapon