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128-581: The engines were first developed in the mid-1950s to launch the R-7 Semyorka , the first intercontinental ballistic missile . The R-7 was later adapted into space launch vehicles and the engines have been improved over several generations. The most recent versions are the RD-107A and RD-108A engines are used to launch the Soyuz-2 , which is in active service as of 2024. The RD-107 was designed under

256-410: A hohlraum or radiation case. The "George" shot of Operation Greenhouse of 9 May 1951 tested the basic concept for the first time on a very small scale. As the first successful (uncontrolled) release of nuclear fusion energy, which made up a small fraction of the 225  kt (940  TJ ) total yield, it raised expectations to a near certainty that the concept would work. On 1 November 1952,

384-622: A Progress cargo spacecraft using a launch vehicle equipped with these engines took place in May 2001. The first human spaceflight launch utilizing these engines took place in October 2002. Currently produced engines are ignited with a pyrotechnic ignition system. Energomash reports a new, hypergolic ignition system (on engines designated 14D21KhZ and 14D22KhZ) are ready for certification and flight tests. Intercontinental ballistic missile An intercontinental ballistic missile ( ICBM )

512-736: A secondary section that consists of fusion fuel . The energy released by the primary compresses the secondary through the process of radiation implosion , at which point it is heated and undergoes nuclear fusion . This process could be continued, with energy from the secondary igniting a third fusion stage; the Soviet Union's AN602 " Tsar Bomba " is thought to have been a three-stage fission-fusion-fusion device. Theoretically by continuing this process thermonuclear weapons with arbitrarily high yield could be constructed. This contrasts with fission weapons, which are limited in yield because only so much fission fuel can be amassed in one place before

640-675: A combination of warheads and massive amounts of countermeasures designed to defeat anti-missile systems ; it was announced by the Russian military as a response to the US Prompt Global Strike . In July 2023, North Korea fired a suspected intercontinental ballistic missile that landed short of Japanese waters. The launch follows North Korea's threat to retaliate against the US for alleged spy plane incursions. The following flight phases can be distinguished: ICBMs usually use

768-430: A design could not produce thermonuclear weapons whose explosive yields could be made arbitrarily large (unlike U.S. designs at that time). The fusion layer wrapped around the fission core could only moderately multiply the fission energy (modern Teller–Ulam designs can multiply it 30-fold). Additionally, the whole fusion stage had to be imploded by conventional explosives, along with the fission core, substantially increasing

896-406: A different rate. This might result in as much as tens of tonnes of unused propellant near the end of the burn. It would generate enormous stress on the structure and cause difficulties in steering due to the mass imbalance. The mixture ratio control system was developed to ensure the simultaneous consumption of propellant mass among the four R-7 boosters. The RD-107 and RD-108 engines are produced at

1024-498: A dozen megatons, which was generally considered enough to destroy even the most hardened practical targets (for example, a control facility such as the Cheyenne Mountain Complex ). Even such large bombs have been replaced by smaller yield nuclear bunker buster bombs. For destruction of cities and non-hardened targets, breaking the mass of a single missile payload down into smaller MIRV bombs in order to spread

1152-456: A few specific incidents outlined in a section below. The basic principle of the Teller–Ulam configuration is the idea that different parts of a thermonuclear weapon can be chained together in stages, with the detonation of each stage providing the energy to ignite the next stage. At a minimum, this implies a primary section that consists of an implosion-type fission bomb (a "trigger"), and

1280-453: A high-yield explosion. A W88 warhead manages to yield up to 475 kilotonnes of TNT (1,990 TJ) with a physics package 68.9 inches (1,750 mm) long, with a maximum diameter of 21.8 inches (550 mm), and by different estimates weighing in a range from 175 to 360 kilograms (386 to 794 lb). The smaller warhead allows more of them to fit onto a single missile and improves basic flight properties such as speed and range. The idea of

1408-488: A massive effort was mounted to re-invent the process. An impurity crucial to the properties of the old Fogbank was omitted during the new process. Only close analysis of new and old batches revealed the nature of that impurity. The manufacturing process used acetonitrile as a solvent , which led to at least three evacuations of the Fogbank plant in 2006. Widely used in the petroleum and pharmaceutical industries, acetonitrile

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1536-400: A minimal independent nuclear deterrent entering its own cold war after an ideological split with the Soviet Union beginning in the early 1960s. After first testing a domestic built nuclear weapon in 1964, it went on to develop various warheads and missiles. Beginning in the early 1970s, the liquid fuelled DF-5 ICBM was developed and used as a satellite launch vehicle in 1975. The DF-5, with

1664-664: A network of binary addition circuits that continually recalculate the missile's position. The inputs to the navigation circuit are set by a general-purpose computer according to a navigational input schedule loaded into the missile before launch. One particular weapon developed by the Soviet Union ;– the Fractional Orbital Bombardment System  – had a partial orbital trajectory, and unlike most ICBMs its target could not be deduced from its orbital flight path. It

1792-576: A possibility. It was first used in thermonuclear weapons with the W76 thermonuclear warhead and produced at a plant in the Y-12 Complex at Oak Ridge, Tennessee , for use in the W76. Production of Fogbank lapsed after the W76 production run ended. The W76 Life Extension Program required more Fogbank to be made. This was complicated by the fact that the original Fogbank's properties were not fully documented, so

1920-628: A range of 10,000 to 12,000 km (6,200 to 7,500 mi)—long enough to strike the Western United States and the Soviet Union—was silo deployed, with the first pair in service by 1981 and possibly twenty missiles in service by the late 1990s. China also deployed the JL-1 Medium-range ballistic missile with a reach of 1,700 kilometres (1,100 mi) aboard the ultimately unsuccessful Type 092 submarine . In 1991,

2048-529: A ready state. Failure rates were very high throughout the early years of ICBM technology. Human spaceflight programs ( Vostok , Mercury , Voskhod , Gemini , etc.) served as a highly visible means of demonstrating confidence in reliability, with successes translating directly to national defense implications. The US was well behind the Soviets in the Space Race and so US President John F. Kennedy increased

2176-474: A single missile to carry several warheads, each of which can strike a different target. The United States , Russia , China , France , India , the United Kingdom , Israel , and North Korea are the only countries known to have operational ICBMs. Pakistan is the only nuclear-armed state that does not possess ICBMs. Early ICBMs had limited precision , which made them suitable for use only against

2304-485: A thermal barrier to keep the fusion fuel filler from becoming too hot, which would spoil the compression. If made of uranium , enriched uranium or plutonium, the tamper captures fast fusion neutrons and undergoes fission itself, increasing the overall explosive yield . Additionally, in most designs the radiation case is also constructed of a material that undergoes fission driven by fast thermonuclear neutrons. Such bombs are classified as two stage weapons. Fast fission of

2432-602: A thermonuclear fusion bomb ignited by a smaller fission bomb was first proposed by Enrico Fermi to his colleague Edward Teller when they were talking at Columbia University in September 1941, at the start of what would become the Manhattan Project . Teller spent much of the Manhattan Project attempting to figure out how to make the design work, preferring it over work on the atomic bomb, and over

2560-459: A variable sized pellet covered in an aqueous solution of potassium permanganate and sodium . Each engine uses four fixed main combustion chambers. The RD-107 has an additional two vernier combustion chambers that can thrust vector in a single plane to supply attitude control. The RD-108 has four verniers to supply full vector control to the Blok-A stage. The single-axle turbopump unit includes

2688-428: Is a ballistic missile with a range greater than 5,500 kilometres (3,400 mi), primarily designed for nuclear weapons delivery (delivering one or more thermonuclear warheads ). Conventional , chemical , and biological weapons can also be delivered with varying effectiveness, but have never been deployed on ICBMs. Most modern designs support multiple independently targetable reentry vehicle (MIRVs), allowing

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2816-557: Is a second-generation nuclear weapon design . Its greater sophistication affords it vastly greater destructive power than first-generation nuclear bombs , a more compact size, a lower mass, or a combination of these benefits. Characteristics of nuclear fusion reactions make possible the use of non-fissile depleted uranium as the weapon's main fuel, thus allowing more efficient use of scarce fissile material such as uranium-235 ( U ) or plutonium-239 ( Pu ). The first full-scale thermonuclear test ( Ivy Mike )

2944-665: Is believed to have deployed a road mobile nuclear ICBM, the Jericho III , which entered service in 2008; an upgraded version is in development. India successfully test fired Agni V , with a strike range of more than 5,000 km (3,100 mi) on 19 April 2012, claiming entry into the ICBM club. The missile's actual range is speculated by foreign researchers to be up to 8,000 km (5,000 mi) with India having downplayed its capabilities to avoid causing concern to other countries. On 15 December 2022, first night trial of Agni-V

3072-531: Is currently led by A.A. Ganin. Modifications to the RD-107 design have led to production of several distinct versions of the engine: Similar modifications have led to several distinct versions of the RD-108: Work on the 14D21 and 14D22 engines started in 1986, with a preliminary design completed in 1993. These engines incorporate a new injector head design to increase specific impulse . The first launch of

3200-461: Is flammable and toxic. Y-12 is the sole producer of Fogbank. A simplified summary of the above explanation is: How exactly the energy is "transported" from the primary to the secondary has been the subject of some disagreement in the open press but is thought to be transmitted through the X-rays and gamma rays that are emitted from the fissioning primary . This energy is then used to compress

3328-526: Is no rocket exhaust or other emissions to mark its position to defenders. The high speeds of the warheads make them difficult to intercept and allow for little warning, striking targets many thousands of kilometers away from the launch site (and due to the possible locations of the submarines: anywhere in the world) within approximately 30 minutes. Many authorities say that missiles also release aluminized balloons, electronic noisemakers, and other decoys intended to confuse interception devices and radars . As

3456-487: Is omitted, by replacing the uranium tamper with one made of lead , for example, the overall explosive force is reduced by approximately half but the amount of fallout is relatively low. The neutron bomb is a hydrogen bomb with an intentionally thin tamper, allowing as many of the fast fusion neutrons as possible to escape. Current technical criticisms of the idea of "foam plasma pressure" focus on unclassified analysis from similar high energy physics fields that indicate that

3584-529: Is one order of magnitude greater than the higher proposed plasma pressures and nearly two orders of magnitude greater than calculated radiation pressure. No mechanism to avoid the absorption of energy into the radiation case wall and the secondary tamper has been suggested, making ablation apparently unavoidable. The other mechanisms appear to be unneeded. United States Department of Defense official declassification reports indicate that foamed plastic materials are or may be used in radiation case liners, and despite

3712-515: Is the Soviet early Sloika design. In essence, the Teller–Ulam configuration relies on at least two instances of implosion occurring: first, the conventional (chemical) explosives in the primary would compress the fissile core, resulting in a fission explosion many times more powerful than that which chemical explosives could achieve alone (first stage). Second, the radiation from the fissioning of

3840-426: Is the fusion fuel, usually a form of lithium deuteride , which is used because it is easier to weaponize than liquefied tritium/deuterium gas. This dry fuel, when bombarded by neutrons, produces tritium, a heavy isotope of hydrogen that can undergo nuclear fusion, along with the deuterium present in the mixture. (See the article on nuclear fusion for a more detailed technical discussion of fusion reactions.) Inside

3968-446: Is the medium by which the outside pressure (force acting on the surface area of the secondary) is transferred to the mass of fusion fuel. The proposed tamper-pusher ablation mechanism posits that the outer layers of the thermonuclear secondary's tamper-pusher are heated so extremely by the primary's X-ray flux that they expand violently and ablate away (fly off). Because total momentum is conserved, this mass of high velocity ejecta impels

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4096-416: Is the primary example). Such processes have resulted in a body of unclassified knowledge about nuclear bombs that is generally consistent with official unclassified information releases and related physics and is thought to be internally consistent, though there are some points of interpretation that are still considered open. The state of public knowledge about the Teller–Ulam design has been mostly shaped from

4224-552: Is thought to be a standard implosion method fission bomb, though likely with a core boosted by small amounts of fusion fuel (usually 1:1 deuterium : tritium gas) for extra efficiency; the fusion fuel releases excess neutrons when heated and compressed, inducing additional fission. When fired, the Pu or U core would be compressed to a smaller sphere by special layers of conventional high explosives arranged around it in an explosive lens pattern, initiating

4352-495: Is thought to have used multiple stages (including more than one tertiary fusion stage) in their 50 Mt (210 PJ) (100 Mt (420 PJ) in intended use) Tsar Bomba. The fissionable jacket could be replaced with lead, as was done with the Tsar Bomba. If any hydrogen bombs have been made from configurations other than those based on the Teller–Ulam design, the fact of it is not publicly known. A possible exception to this

4480-409: Is widely assumed to be beryllium , which fits that description and would also moderate the neutron flux from the primary. Some material to absorb and re-radiate the X-rays in a particular manner may also be used. Candidates for the "special material" are polystyrene and a substance called " Fogbank ", an unclassified codename. Fogbank's composition is classified, though aerogel has been suggested as

4608-450: The Arrow missile in 1998, but it is mainly designed to intercept shorter-ranged theater ballistic missiles, not ICBMs. The Alaska-based United States national missile defense system attained initial operational capability in 2004. ICBMs can be deployed from multiple platforms: The last three kinds are mobile and therefore hard to detect prior to a missile launch. During storage, one of

4736-626: The JSC Kuznetsov plant in Samara, Russia , under the supervision of the Privolzhskiy branch of NPO Energomash , also known as the Volga branch. The Privolzhsky branch was organized as a branch of OKB-456 in 1958, specifically for the manufacture of RD-107 and RD-108 engines. The branch was led by Y.D. Solovjev until 1960, then by R.I. Zelenev until 1975, then by A.F. Udalov until 1978, and

4864-511: The LGM-30 Minuteman , Polaris and Skybolt . Modern ICBMs tend to be smaller than their ancestors, due to increased accuracy and smaller and lighter warheads, and use solid fuels, making them less useful as orbital launch vehicles. The Western view of the deployment of these systems was governed by the strategic theory of mutual assured destruction . In the 1950s and 1960s, development began on anti-ballistic missile systems by both

4992-570: The Trident II SLBM, had a prolate primary (code-named Komodo ) and a spherical secondary (code-named Cursa ) inside a specially shaped radiation case (known as the "peanut" for its shape). The value of an egg-shaped primary lies apparently in the fact that a MIRV warhead is limited by the diameter of the primary: if an egg-shaped primary can be made to work properly, then the MIRV warhead can be made considerably smaller yet still deliver

5120-498: The USSR /Russia preferred ICBM designs that use hypergolic liquid fuels, which can be stored at room temperature for more than a few years. Once the booster falls away, the remaining "bus" releases several warheads, each of which continues on its own unpowered ballistic trajectory , much like an artillery shell or cannonball. The warhead is encased in a cone-shaped reentry vehicle and is difficult to detect in this phase of flight as there

5248-612: The W-80 the gas expansion velocity is roughly 410 km/s (41 cm/μs) and the implosion velocity 570 km/s (57 cm/μs). The pressure due to the ablating material is calculated to be 5.3  billion bars (530  trillion pascals ) in the Ivy Mike device and 64 billion bars (6.4 quadrillion pascals) in the W-80 device. Comparing the three mechanisms proposed, it can be seen that: The calculated ablation pressure

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5376-547: The W47 warhead deployed on Polaris ballistic missile submarines , megaton-class warheads were as small as 18 inches (0.46 m) in diameter and 720 pounds (330 kg) in weight. Further innovation in miniaturizing warheads was accomplished by the mid-1970s, when versions of the Teller–Ulam design were created that could fit ten or more warheads on the end of a small MIRVed missile. The first Soviet fusion design, developed by Andrei Sakharov and Vitaly Ginzburg in 1949 (before

5504-464: The cryogenic fuel liquid oxygen boiled off and caused ice formation, and therefore fueling the rocket was necessary before launch. This procedure was a source of significant operational delay and might allow the missiles to be destroyed by enemy counterparts before they could be used. To resolve this problem Nazi Germany invented the missile silo that protected the missile from Strategic Bombing and also hid fueling operations underground. Although

5632-558: The neutron flux from the primary to prematurely begin heating the secondary, weakening the compression enough to prevent any fusion. There is very little detailed information in the open literature about the mechanism of the interstage. One of the best sources is a simplified diagram of a British thermonuclear weapon similar to the American W80 warhead. It was released by Greenpeace in a report titled "Dual Use Nuclear Technology" . The major components and their arrangement are in

5760-408: The nuclear chain reaction that powers the conventional "atomic bomb". The secondary is usually shown as a column of fusion fuel and other components wrapped in many layers. Around the column is first a "pusher- tamper ", a heavy layer of uranium-238 ( U ) or lead that helps compress the fusion fuel (and, in the case of uranium, may eventually undergo fission itself). Inside this

5888-460: The secondary . The crucial detail of how the X-rays create the pressure is the main remaining disputed point in the unclassified press. There are three proposed theories: The radiation pressure exerted by the large quantity of X-ray photons inside the closed casing might be enough to compress the secondary. Electromagnetic radiation such as X-rays or light carries momentum and exerts a force on any surface it strikes. The pressure of radiation at

6016-409: The 32-metre-tall (105 ft) Unha-3 rocket. The United States claimed that the launch was in fact a way to test an ICBM. (See Timeline of first orbital launches by country .) In early July 2017, North Korea claimed for the first time to have tested successfully an ICBM capable of carrying a large thermonuclear warhead. In July 2014, China announced the development of its newest generation of ICBM,

6144-935: The A9/A10 rocket was tested a few times in January and February 1945. After the war, the US executed Operation Paperclip , which took von Braun and hundreds of other leading Nazi scientists to the United States to develop IRBMs , ICBMs, and launchers for the US Army. This technology was predicted by US General of the Army Hap Arnold , who wrote in 1943: Someday, not too distant, there can come streaking out of somewhere – we won't be able to hear it, it will come so fast – some kind of gadget with an explosive so powerful that one projectile will be able to wipe out completely this city of Washington. After World War II,

6272-703: The American missile defense batteries in California and Alaska. New development of ICBM technology are ICBMs able to carry hypersonic glide vehicles as a payload such as RS-28 Sarmat . On 12 March 2024 India announced that it had joined a very limited group of countries, which are capable of firing multiple warheads on a single ICBM. The announcement came after successfully testing multiple independently targetable reentry vehicle (MIRV) technology. [REDACTED] Russia [REDACTED] Russia [REDACTED] Russia [REDACTED] Russia Russia,

6400-651: The Americans and Soviets. Such systems were restricted by the 1972 Anti-Ballistic Missile Treaty . The first successful ABM test was conducted by the Soviets in 1961, which later deployed a fully operational system defending Moscow in the 1970s (see Moscow ABM system ). The 1972 SALT treaty froze the number of ICBM launchers of both the Americans and the Soviets at existing levels and allowed new submarine -based SLBM launchers only if an equal number of land-based ICBM launchers were dismantled. Subsequent talks, called SALT II, were held from 1972 to 1979 and actually reduced

6528-521: The Americans and the Soviets started rocket research programs based on the V-2 and other German wartime designs. Each branch of the US military started its own programs, leading to considerable duplication of effort. In the Soviet Union, rocket research was centrally organized although several teams worked on different designs. The US initiated ICBM research in 1946 with the RTV-A-2 Hiroc project. This

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6656-676: The Atlas. Due to the improvements in engine technology and guidance systems the Titan I overtook the Atlas. In the Soviet Union, early development was focused on missiles able to attack European targets. That changed in 1953, when Sergei Korolyov was directed to start development of a true ICBM able to deliver newly developed hydrogen bombs. Given steady funding throughout, the R-7 developed with some speed. The first launch took place on 15 May 1957 and led to an unintended crash 400 km (250 mi) from

6784-524: The British fusion bomb, with Sir William Penney in charge of the project. British knowledge on how to make a thermonuclear fusion bomb was rudimentary, and at the time the United States was not exchanging any nuclear knowledge because of the Atomic Energy Act of 1946 . The United Kingdom had worked closely with the Americans on the Manhattan Project. British access to nuclear weapons information

6912-522: The Dongfeng-41 ( DF-41 ), which has a range of 12,000 kilometres (7,500 miles), capable of reaching the United States, and which analysts believe is capable of being outfitted with MIRV technology. Most countries in the early stages of developing ICBMs have used liquid propellants, with the known exceptions being the Indian Agni-V , the planned but cancelled South African RSA-4 ICBM, and

7040-526: The Soviet Union, United Kingdom, France, China and India. The thermonuclear Tsar Bomba was the most powerful bomb ever detonated. As thermonuclear weapons represent the most efficient design for weapon energy yield in weapons with yields above 50 kilotons of TNT (210 TJ), virtually all the nuclear weapons of this size deployed by the five nuclear-weapon states under the Non-Proliferation Treaty today are thermonuclear weapons using

7168-459: The Soviet testing of their first thermonuclear weapon , but it was not until 1954 that the Atlas missile program was given the highest national priority. The Atlas A first flew on 11 June 1957; the flight lasted only about 24 seconds before the rocket exploded. The first successful flight of an Atlas missile to full range occurred 28 November 1958. The first armed version of the Atlas, the Atlas D,

7296-475: The Soviets had a working fission bomb), was dubbed the Sloika , after a Russian layer cake , and was not of the Teller–Ulam configuration. It used alternating layers of fissile material and lithium deuteride fusion fuel spiked with tritium (this was later dubbed Sakharov's "First Idea"). Though nuclear fusion might have been technically achievable, it did not have the scaling property of a "staged" weapon. Thus, such

7424-498: The Soviets searched for an alternative design. The "Second Idea", as Sakharov referred to it in his memoirs, was a previous proposal by Ginzburg in November 1948 to use lithium deuteride in the bomb, which would, in the course of being bombarded by neutrons, produce tritium and free deuterium. In late 1953 physicist Viktor Davidenko achieved the first breakthrough of staging the reactions. The next breakthrough of radiation implosion

7552-673: The Teller–Ulam configuration was tested at full scale in the "Ivy Mike" shot at an island in the Enewetak Atoll , with a yield of 10.4  Mt (44  PJ ) (over 450 times more powerful than the bomb dropped on Nagasaki during World War II ). The device, dubbed the Sausage , used an extra-large fission bomb as a "trigger" and liquid deuterium—kept in its liquid state by 20 short tons (18  t ) of cryogenic equipment—as its fusion fuel, and weighed around 80 short tons (73  t ) altogether. The liquid deuterium fuel of Ivy Mike

7680-429: The Teller–Ulam design. Detailed knowledge of fission and fusion weapons is classified to some degree in virtually every industrialized country . In the United States, such knowledge can by default be classified as " Restricted Data ", even if it is created by persons who are not government employees or associated with weapons programs, in a legal doctrine known as " born secret " (though the constitutional standing of

7808-435: The U.S. and Soviets, achieving only approximately 300 kt (1,300 TJ). The second test Orange Herald was the modified fission bomb and produced 720 kt (3,000 TJ)—making it the largest fission explosion ever. At the time almost everyone (including the pilots of the plane that dropped it) thought that this was a fusion bomb. This bomb was put into service in 1958. A second prototype fusion bomb, Purple Granite ,

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7936-493: The U.S. government has attempted to censor weapons information in the public press , with limited success. According to the New York Times , physicist Kenneth W. Ford defied government orders to remove classified information from his book Building the H Bomb: A Personal History . Ford claims he used only pre-existing information and even submitted a manuscript to the government, which wanted to remove entire sections of

8064-685: The United States and the Soviet Union agreed in the START I treaty to reduce their deployed ICBMs and attributed warheads. As of 2016 , all five of the nations with permanent seats on the United Nations Security Council have fully operational long-range ballistic missile systems; Russia, the United States, and China also have land-based ICBMs (the US missiles are silo-based, while China and Russia have both silo and road-mobile ( DF-31 , RT-2PM2 Topol-M missiles). Israel

8192-943: The United States, China, North Korea, India and Israel are the only countries currently known to possess land-based ICBMs. The United States currently operates 405 ICBMs in three USAF bases. The only model deployed is LGM-30G Minuteman-III . All previous USAF Minuteman II missiles were destroyed in accordance with START II , and their launch silos have been sealed or sold to the public. The powerful MIRV-capable Peacekeeper missiles were phased out in 2005. The Russian Strategic Rocket Forces have 286 ICBMs able to deliver 958 nuclear warheads: 46 silo-based R-36M2 (SS-18) , 30 silo-based UR-100N (SS-19), 36 mobile RT-2PM "Topol" (SS-25) , 60 silo-based RT-2UTTH "Topol M" (SS-27) , 18 mobile RT-2UTTH "Topol M" (SS-27) , 84 mobile RS-24 "Yars" (SS-29), and 12 silo-based RS-24 "Yars" (SS-29). Thermonuclear weapon A thermonuclear weapon , fusion weapon or hydrogen bomb ( H bomb )

8320-494: The X-ray energy impinging on its pusher/ tamper. This compresses the entire secondary stage and drives up the density of the plutonium spark plug. The density of the plutonium fuel rises to such an extent that the spark plug is driven into a supercritical state, and it begins a nuclear fission chain reaction . The fission products of this chain reaction heat the highly compressed (and thus super dense) thermonuclear fuel surrounding

8448-481: The additional warheads; hence, most ABM system proposals have been judged to be impractical. The first operational ABM systems were deployed in the United States during the 1970s. The Safeguard ABM facility, located in North Dakota, was operational from 1975 to 1976. The Soviets deployed their ABM-1 Galosh system around Moscow in the 1970s, which remains in service. Israel deployed a national ABM system based on

8576-411: The amount of chemical explosives needed. The first Sloika design test, RDS-6s , was detonated in 1953 with a yield equivalent to 400 kt (1,700 TJ) ( 15%- 20% from fusion). Attempts to use a Sloika design to achieve megaton-range results proved unfeasible. After the United States tested the "Ivy Mike" thermonuclear device in November 1952, proving that a multimegaton bomb could be created,

8704-446: The book for concern that foreign states could use the information. Though large quantities of vague data have been officially released—and larger quantities of vague data have been unofficially leaked by former bomb designers—most public descriptions of nuclear weapon design details rely to some degree on speculation, reverse engineering from known information, or comparison with similar fields of physics ( inertial confinement fusion

8832-481: The casing to a plasma, which then re-radiated radiation into the secondary's pusher, causing its surface to ablate and driving it inwards, compressing the secondary, igniting the sparkplug, and causing the fusion reaction. The general applicability of this principle is unclear. In 1999 a reporter for the San Jose Mercury News reported that the U.S. W88 nuclear warhead, a small MIRVed warhead used on

8960-440: The casing's circumference. The neutron guns are tilted so the neutron emitting end of each gun end is pointed towards the central axis of the bomb. Neutrons from each neutron gun pass through and are focused by the neutron focus lens towards the centre of primary in order to boost the initial fissioning of the plutonium. A " polystyrene Polarizer/Plasma Source" is also shown (see below). The first U.S. government document to mention

9088-412: The conditions needed for fusion, and the idea of staging or placing a separate thermonuclear component outside a fission primary component, and somehow using the primary to compress the secondary. Teller then realized that the gamma and X-ray radiation produced in the primary could transfer enough energy into the secondary to create a successful implosion and fusion burn, if the whole assembly was wrapped in

9216-523: The danger of its accidentally becoming supercritical becomes too great. Surrounding the other components is a hohlraum or radiation case , a container that traps the first stage or primary's energy inside temporarily. The outside of this radiation case, which is also normally the outside casing of the bomb, is the only direct visual evidence publicly available of any thermonuclear bomb component's configuration. Numerous photographs of various thermonuclear bomb exteriors have been declassified. The primary

9344-416: The decision to go forward with the development of the new weapon. Teller and other U.S. physicists struggled to find a workable design. Stanislaw Ulam , a co-worker of Teller, made the first key conceptual leaps towards a workable fusion design. Ulam's two innovations that rendered the fusion bomb practical were that compression of the thermonuclear fuel before extreme heating was a practical path towards

9472-424: The diagram, though details are almost absent; what scattered details it does include likely have intentional omissions or inaccuracies. They are labeled "End-cap and Neutron Focus Lens" and "Reflector Wrap"; the former channels neutrons to the U / Pu Spark Plug while the latter refers to an X-ray reflector; typically a cylinder made of an X-ray opaque material such as uranium with

9600-599: The direction of Valentin Glushko at the Experimental Design Bureau (OKB-456) between 1954 and 1957. It uses liquid oxygen and kerosene as propellants operating in a gas generator cycle. As was typical by all the descendants of the V-2 rocket technology, the turbine is driven by steam generated by catalytic decomposition of H₂O₂ . The steam generator uses solid F-30-P-G catalyst. These are based on

9728-479: The doctrine has been at times called into question; see United States v. Progressive, Inc. ). Born secret is rarely invoked for cases of private speculation. The official policy of the United States Department of Energy has been not to acknowledge the leaking of design information, as such acknowledgment would potentially validate the information as accurate. In a small number of prior cases,

9856-414: The effects of that absorbed energy led to the third mechanism: ablation . The outer casing of the secondary assembly is called the "tamper-pusher". The purpose of a tamper in an implosion bomb is to delay the expansion of the reacting fuel supply (which is very hot dense plasma) until the fuel is fully consumed and the explosion runs to completion. The same tamper material serves also as a pusher in that it

9984-512: The energy of the explosions into a "pancake" area is far more efficient in terms of area-destruction per unit of bomb energy. This also applies to single bombs deliverable by cruise missile or other system, such as a bomber, resulting in most operational warheads in the U.S. program having yields of less than 500 kt (2,100 TJ). In his 1995 book Dark Sun: The Making of the Hydrogen Bomb , author Richard Rhodes describes in detail

10112-519: The far more powerful Super. The debate covered matters that were alternatively strategic, pragmatic, and moral. In their Report of the General Advisory Committee, Robert Oppenheimer and colleagues concluded that "[t]he extreme danger to mankind inherent in the proposal [to develop thermonuclear weapons] wholly outweighs any military advantage." Despite the objections raised, on 31 January 1950, President Harry S. Truman made

10240-436: The fissioning of the final natural uranium tamper, something that could not normally be achieved without the neutron flux provided by the fusion reactions in secondary or tertiary stages. Such designs are suggested to be capable of being scaled up to an arbitrary large yield (with apparently as many fusion stages as desired), potentially to the level of a " doomsday device ." However, usually such weapons were not more than

10368-504: The gap between the Neutron Focus Lens (in the center) and the outer casing near the primary. It separates the primary from the secondary and performs the same function as the previous reflector. There are about six neutron guns (seen here from Sandia National Laboratories ) each protruding through the outer edge of the reflector with one end in each section; all are clamped to the carriage and arranged more or less evenly around

10496-462: The intensities seen in everyday life, such as sunlight striking a surface, is usually imperceptible, but at the extreme intensities found in a thermonuclear bomb the pressure is enormous. For two thermonuclear bombs for which the general size and primary characteristics are well understood, the Ivy Mike test bomb and the modern W-80 cruise missile warhead variant of the W-61 design, the radiation pressure

10624-420: The internal components of the "Ivy Mike" Sausage device, based on information obtained from extensive interviews with the scientists and engineers who assembled it. According to Rhodes, the actual mechanism for the compression of the secondary was a combination of the radiation pressure, foam plasma pressure, and tamper-pusher ablation theories; the radiation from the primary heated the polyethylene foam lining of

10752-504: The interstage was only recently released to the public promoting the 2004 initiation of the Reliable Replacement Warhead (RRW) Program. A graphic includes blurbs describing the potential advantage of a RRW on a part-by-part level, with the interstage blurb saying a new design would replace "toxic, brittle material" and "expensive 'special' material... [that require] unique facilities". The "toxic, brittle material"

10880-485: The largest targets , such as cities. They were seen as a "safe" basing option, one that would keep the deterrent force close to home where it would be difficult to attack. Attacks against military targets (especially hardened ones) demanded the use of a more precise, crewed bomber . Second- and third-generation designs (such as the LGM-118 Peacekeeper ) dramatically improved accuracy to the point where even

11008-581: The last year of the project he was assigned exclusively to the task. However once World War II ended, there was little impetus to devote many resources to the Super , as it was then known. The first atomic bomb test by the Soviet Union in August 1949 came earlier than expected by Americans, and over the next several months there was an intense debate within the U.S. government, military, and scientific communities regarding whether to proceed with development of

11136-415: The layer of fuel is the " spark plug ", a hollow column of fissile material ( Pu or U ) often boosted by deuterium gas. The spark plug, when compressed, can undergo nuclear fission (because of the shape, it is not a critical mass without compression). The tertiary, if one is present, would be set below the secondary and probably be made of the same materials. Separating

11264-432: The low direct plasma pressure they may be of use in delaying the ablation until energy has distributed evenly and a sufficient fraction has reached the secondary's tamper/pusher. Richard Rhodes ' book Dark Sun stated that a 1-inch-thick (25 mm) layer of plastic foam was fixed to the lead liner of the inside of the Ivy Mike steel casing using copper nails. Rhodes quotes several designers of that bomb explaining that

11392-578: The most important features of the missile is its serviceability. One of the key features of the first computer-controlled ICBM, the Minuteman missile , was that it could quickly and easily use its computer to test itself. After launch, a booster pushes the missile and then falls away. Most modern boosters are Solid-propellant rocket motors , which can be stored easily for long periods of time. Early missiles used liquid-fueled rocket motors . Many liquid-fueled ICBMs could not be kept fueled at all times as

11520-713: The nearby detonation of friendly warheads), one neutron-resistant material developed for this purpose in the UK is three-dimensional quartz phenolic . Circular error probable is crucial, because halving the circular error probable decreases the needed warhead energy by a factor of four . Accuracy is limited by the accuracy of the navigation system and the available geodetic information. Strategic missile systems are thought to use custom integrated circuits designed to calculate navigational differential equations thousands to millions of FLOPS in order to reduce navigational errors caused by calculation alone. These circuits are usually

11648-566: The now in service Israeli Jericho III . The RS-28 Sarmat (Russian: РС-28 Сармат; NATO reporting name : SATAN 2), is a Russian liquid-fueled , MIRV -equipped, super-heavy thermonuclear armed intercontinental ballistic missile in development by the Makeyev Rocket Design Bureau from 2009, intended to replace the previous R-36 missile . Its large payload would allow for up to 10 heavy warheads or 15 lighter ones or up to 24 hypersonic glide vehicles Yu-74 , or

11776-526: The nuclear warhead reenters the Earth's atmosphere, its high speed causes compression of the air, leading to a dramatic rise in temperature which would destroy it, if it were not shielded in some way. In one design, warhead components are contained within an aluminium honeycomb substructure , sheathed in a pyrolytic carbon - epoxy synthetic resin composite material heat shield. Warheads are also often radiation-hardened (to protect against nuclear armed ABMs or

11904-649: The number of nuclear warheads held by the US and Soviets. SALT II was never ratified by the US Senate , but its terms were honored by both sides until 1986, when the Reagan administration "withdrew" after it had accused the Soviets of violating the pact. In the 1980s, President Ronald Reagan launched the Strategic Defense Initiative as well as the MX and Midgetman ICBM programs. China developed

12032-424: The outer radiation case, with the components coming to a thermal equilibrium , and the effects of that thermal energy are then analyzed. The energy is mostly deposited within about one X-ray optical thickness of the tamper/pusher outer surface, and the temperature of that layer can then be calculated. The velocity at which the surface then expands outwards is calculated and, from a basic Newtonian momentum balance,

12160-438: The plastic foam layer inside the outer case is to delay ablation and thus recoil of the outer case: if the foam were not there, metal would ablate from the inside of the outer case with a large impulse, causing the casing to recoil outwards rapidly. The purpose of the casing is to contain the explosion for as long as possible, allowing as much X-ray ablation of the metallic surface of the secondary stage as possible, so it compresses

12288-413: The pressure produced by such a plasma would only be a small multiplier of the basic photon pressure within the radiation case, and also that the known foam materials intrinsically have a very low absorption efficiency of the gamma ray and X-ray radiation from the primary. Most of the energy produced would be absorbed by either the walls of the radiation case or the tamper around the secondary. Analyzing

12416-519: The primary and secondary assemblies placed within an enclosure called a radiation case, which confines the X-ray energy and resists its outward pressure. The distance separating the two assemblies ensures that debris fragments from the fission primary (which move much more slowly than X-ray photons ) cannot disassemble the secondary before the fusion explosion runs to completion. The secondary fusion stage—consisting of outer pusher/ tamper , fusion fuel filler and central plutonium spark plug—is imploded by

12544-442: The primary and secondary at either end. It does not reflect like a mirror; instead, it gets heated to a high temperature by the X-ray flux from the primary, then it emits more evenly spread X-rays that travel to the secondary, causing what is known as radiation implosion . In Ivy Mike , gold was used as a coating over the uranium to enhance the blackbody effect. Next comes the "Reflector/Neutron Gun Carriage". The reflector seals

12672-425: The primary would be used to compress and ignite the secondary fusion stage, resulting in a fusion explosion many times more powerful than the fission explosion alone. This chain of compression could conceivably be continued with an arbitrary number of tertiary fusion stages, each igniting more fusion fuel in the next stage although this is debated. Finally, efficient bombs (but not so-called neutron bombs ) end with

12800-448: The pure element or in modern weapons lithium deuteride . For this reason, thermonuclear weapons are often colloquially called hydrogen bombs or H-bombs . A fusion explosion begins with the detonation of the fission primary stage. Its temperature soars past 100 million kelvin , causing it to glow intensely with thermal ("soft") X-rays . These X-rays flood the void (the "radiation channel" often filled with polystyrene foam ) between

12928-418: The rest of the tamper-pusher to recoil inwards with tremendous force, crushing the fusion fuel and the spark plug. The tamper-pusher is built robustly enough to insulate the fusion fuel from the extreme heat outside; otherwise, the compression would be spoiled. Rough calculations for the basic ablation effect are relatively simple: the energy from the primary is distributed evenly onto all of the surfaces within

13056-450: The secondary efficiently, maximizing the fusion yield. Plastic foam has a low density, so causes a smaller impulse when it ablates than metal does. Possible variations to the weapon design have been proposed: Most bombs do not apparently have tertiary "stages"—that is, third compression stage(s), which are additional fusion stages compressed by a previous fusion stage. The fissioning of the last blanket of uranium, which provides about half

13184-422: The secondary from the primary is the interstage . The fissioning primary produces four types of energy: 1) expanding hot gases from high explosive charges that implode the primary; 2) superheated plasma that was originally the bomb's fissile material and its tamper; 3) the electromagnetic radiation ; and 4) the neutrons from the primary's nuclear detonation. The interstage is responsible for accurately modulating

13312-594: The secondary stages by radiation implosion. Because of these difficulties, in 1955 Prime Minister Anthony Eden agreed to a secret plan, whereby if the Aldermaston scientists failed or were greatly delayed in developing the fusion bomb, it would be replaced by an extremely large fission bomb. In 1957 the Operation Grapple tests were carried out. The first test, Green Granite, was a prototype fusion bomb that failed to produce equivalent yields compared to

13440-469: The site. The first successful test followed on 21 August 1957; the R-7 flew over 6,000 km (3,700 mi) and became the world's first ICBM. The first strategic-missile unit became operational on 9 February 1959 at Plesetsk in north-west Russia. It was the same R-7 launch vehicle that placed the first artificial satellite in space, Sputnik , on 4 October 1957. The first human spaceflight in history

13568-477: The smallest point targets can be successfully attacked. ICBMs are differentiated by having greater range and speed than other ballistic missiles: intermediate-range ballistic missiles (IRBMs), medium-range ballistic missiles (MRBMs), short-range ballistic missiles (SRBMs) and tactical ballistic missiles . The first practical design for an ICBM grew out of Nazi Germany 's V-2 rocket program. The liquid-fueled V-2, designed by Wernher von Braun and his team,

13696-418: The spark plug to around 300 million kelvin, igniting fusion reactions between fusion fuel nuclei. In modern weapons fueled by lithium deuteride, the fissioning plutonium spark plug also emits free neutrons that collide with lithium nuclei and supply the tritium component of the thermonuclear fuel. The secondary's relatively massive tamper (which resists outward expansion as the explosion proceeds) also serves as

13824-486: The stakes with the Apollo program , which used Saturn rocket technology that had been funded by President Dwight D. Eisenhower . These early ICBMs also formed the basis of many space launch systems. Examples include R-7 , Atlas , Redstone , Titan , and Proton , which was derived from the earlier ICBMs but never deployed as an ICBM. The Eisenhower administration supported the development of solid-fueled missiles such as

13952-549: The steam driven turbine, an oxidizer pump, a fuel pump, and a nitrogen gas generator for tank pressurization. The RD-107 engines are used in each of the boosters of the Soyuz-2 rocket, and a single RD-108 is used in the Blok-A stage (the central 1st stage). One important innovation of this engine was the capability to use variable mixture ratio between fuel and oxidizer. The natural variations in manufacturing between each engine meant that without an active propellant consumption control, each booster could deplete oxygen and fuel at

14080-407: The tamper and radiation case is the main contribution to the total yield and is the dominant process that produces radioactive fission product fallout . Before Ivy Mike, Operation Greenhouse in 1951 was the first American nuclear test series to test principles that led to the development of thermonuclear weapons. Sufficient fission was achieved to boost the associated fusion device, and enough

14208-428: The trajectory which optimizes range for a given amount of payload (the minimum-energy trajectory ); an alternative is a depressed trajectory , which allows less payload, shorter flight time, and has a much lower apogee. Modern ICBMs typically carry multiple independently targetable reentry vehicles ( MIRVs ), each of which carries a separate nuclear warhead , allowing a single missile to hit multiple targets. MIRV

14336-404: The transfer of energy from the primary to the secondary. It must direct the hot gases, plasma, electromagnetic radiation and neutrons toward the right place at the right time. Less than optimal interstage designs have resulted in the secondary failing to work entirely on multiple shots, known as a " fissile fizzle ". The Castle Koon shot of Operation Castle is a good example; a small flaw allowed

14464-412: The velocity at which the rest of the tamper implodes inwards. Applying the more detailed form of those calculations to the Ivy Mike device yields vaporized pusher gas expansion velocity of 290 kilometres per second (29 cm/μs) and an implosion velocity of perhaps 400 km/s (40 cm/μs) if + 3 ⁄ 4 of the total tamper/pusher mass is ablated off, the most energy efficient proportion. For

14592-404: The weapon (with the foam) would be as follows: This would complete the fission-fusion-fission sequence. Fusion, unlike fission, is relatively "clean"—it releases energy but no harmful radioactive products or large amounts of nuclear fallout . The fission reactions though, especially the last fission reactions, release a tremendous amount of fission products and fallout. If the last fission stage

14720-500: The yield in large bombs, does not count as a "stage" in this terminology. The U.S. tested three-stage bombs in several explosions during Operation Redwing but is thought to have fielded only one such tertiary model, i.e., a bomb in which a fission stage, followed by a fusion stage, finally compresses yet another fusion stage. This U.S. design was the heavy but highly efficient (i.e., nuclear weapon yield per unit bomb weight) 25 Mt (100 PJ) B41 nuclear bomb . The Soviet Union

14848-432: Was a three-stage effort with the ICBM development not starting until the third stage. However, funding was cut in 1948 after only three partially successful launches of the second stage design, that was used to test variations of the V-2 design. With overwhelming air superiority and truly intercontinental bombers, the newly formed US Air Force did not take the problem of ICBM development seriously. Things changed in 1953 with

14976-518: Was accomplished on a derivative of R-7, Vostok , on 12 April 1961 , by Soviet cosmonaut Yuri Gagarin . A heavily modernized version of the R-7 is still used as the launch vehicle for the Soviet/Russian Soyuz spacecraft , marking more than 60 years of operational history of Sergei Korolyov 's original rocket design. The R-7 and Atlas each required a large launch facility, making them vulnerable to attack, and could not be kept in

15104-534: Was an outgrowth of the rapidly shrinking size and weight of modern warheads and the Strategic Arms Limitation Treaties ( SALT I and SALT II ), which imposed limitations on the number of launch vehicles. It has also proved to be an "easy answer" to proposed deployments of anti-ballistic missile (ABM) systems: It is far less expensive to add more warheads to an existing missile system than to build an ABM system capable of shooting down

15232-486: Was calculated to be 73 × 10 ^   bar (7.3  TPa ) for the Ivy Mike design and 1,400 × 10 ^   bar (140  TPa ) for the W-80. Foam plasma pressure is the concept that Chuck Hansen introduced during the Progressive case, based on research that located declassified documents listing special foams as liner components within the radiation case of thermonuclear weapons. The sequence of firing

15360-451: Was carried out by the United States in 1952, and the concept has since been employed by most of the world's nuclear powers in the design of their weapons. Modern fusion weapons essentially consist of two main components: a nuclear fission primary stage (fueled by U or Pu ) and a separate nuclear fusion secondary stage containing thermonuclear fuel: heavy isotopes of hydrogen ( deuterium and tritium ) as

15488-415: Was cut off by the United States at one point due to concerns about Soviet espionage. Full cooperation was not reestablished until an agreement governing the handling of secret information and other issues was signed. However, the British were allowed to observe the U.S. Castle tests and used sampling aircraft in the mushroom clouds , providing them with clear, direct evidence of the compression produced in

15616-418: Was declared operational in January 1959 at Vandenberg, although it had not yet flown. The first test flight was carried out on 9 July 1959, and the missile was accepted for service on 1 September. The Titan I was another US multistage ICBM, with a successful launch February 5, 1959, with Titan I A3. Unlike the Atlas, the Titan I was a two-stage missile, rather than three. The Titan was larger, yet lighter, than

15744-416: Was decommissioned in compliance with arms control agreements, which address the maximum range of ICBMs and prohibit orbital or fractional-orbital weapons. However, according to reports, Russia is working on the new Sarmat ICBM which leverages Fractional Orbital Bombardment concepts to use a Southern polar approach instead of flying over the northern polar regions. Using that approach, it is theorized, avoids

15872-549: Was discovered and developed by Sakharov and Yakov Zel'dovich in early 1954. Sakharov's "Third Idea", as the Teller–Ulam design was known in the USSR, was tested in the shot " RDS-37 " in November 1955 with a yield of 1.6 Mt (6.7 PJ). The Soviets demonstrated the power of the staging concept in October 1961, when they detonated the massive and unwieldy Tsar Bomba. It was the largest nuclear weapon developed and tested by any country. In 1954 work began at Aldermaston to develop

16000-509: Was impractical for a deployable weapon, and the next advance was to use a solid lithium deuteride fusion fuel instead. In 1954 this was tested in the " Castle Bravo " shot (the device was code-named Shrimp ), which had a yield of 15  Mt (63  PJ ) (2.5 times expected) and is the largest U.S. bomb ever tested. Efforts shifted towards developing miniaturized Teller–Ulam weapons that could fit into intercontinental ballistic missiles and submarine-launched ballistic missiles . By 1960, with

16128-463: Was learned to achieve a full-scale device within a year. The design of all modern thermonuclear weapons in the United States is known as the Teller–Ulam configuration for its two chief contributors, Edward Teller and Stanisław Ulam , who developed it in 1951 for the United States, with certain concepts developed with the contribution of physicist John von Neumann . Similar devices were developed by

16256-408: Was successfully carried out by SFC from Abdul Kalam Island, Odisha. The missile is now 20 percent lighter because the use of composite materials rather than steel material. The range has been increased to 7,000 km. By 2012 there was speculation by some intelligence agencies that North Korea is developing an ICBM. North Korea successfully put a satellite into space on 12 December 2012 using

16384-470: Was then widely used by Nazi Germany from mid-1944 until March 1945 to bomb British and Belgian cities, particularly Antwerp and London. Under Projekt Amerika, von Braun's team developed the A9/10 ICBM, intended for use in bombing New York and other American cities. Initially intended to be guided by radio, it was changed to be a piloted craft after the failure of Operation Elster . The second stage of

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