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Nuclear Blackout
Nuclear blackout, also known as fireball blackout or radar blackout, is an effect caused by explosions of nuclear weapons that disturbs radio communications and causes radar systems to be blacked out or heavily refracted so they can no longer be used for accurate tracking and guidance. Within the atmosphere, the effect is caused by the large volume of ionized air created by the energy of the explosion, while above the atmosphere it is due to the action of high-energy beta particles released from the decaying bomb debris. At high altitudes, the effect can spread over large areas, hundreds of kilometers. The effect slowly fades as the fireball dissipates. The effect was known from the earliest days of nuclear testing when radar systems were used to track the nuclear mushroom clouds at very long distances. Its extended effects when exploded outside the atmosphere were first noticed in 1958 as part of the Hardtack and Argus nuclear tests, which caused widespread radio interference exte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions ( thermonuclear bomb), producing a nuclear explosion. Both bomb types release large quantities of energy from relatively small amounts of matter. The first test of a fission ("atomic") bomb released an amount of energy approximately equal to . The first thermonuclear ("hydrogen") bomb test released energy approximately equal to . Nuclear bombs have had yields between 10 tons TNT (the W54) and 50 megatons for the Tsar Bomba (see TNT equivalent). A thermonuclear weapon weighing as little as can release energy equal to more than . A nuclear device no larger than a conventional bomb can devastate an entire city by blast, fire, and radiation. Since they are weapons of mass destruction, the proliferation of nuclear weapons is a focus of international relations policy. Nuclear weapons have been d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Mechanics
Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, quantum field theory, quantum technology, and quantum information science. Classical physics, the collection of theories that existed before the advent of quantum mechanics, describes many aspects of nature at an ordinary (macroscopic) scale, but is not sufficient for describing them at small (atomic and subatomic) scales. Most theories in classical physics can be derived from quantum mechanics as an approximation valid at large (macroscopic) scale. Quantum mechanics differs from classical physics in that energy, momentum, angular momentum, and other quantities of a bound system are restricted to discrete values ( quantization); objects have characteristics of both particles and waves (wave–particle duality); and there are limits to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Weapons
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions (thermonuclear bomb), producing a nuclear explosion. Both bomb types release large quantities of energy from relatively small amounts of matter. The first test of a fission ("atomic") bomb released an amount of energy approximately equal to . The first thermonuclear ("hydrogen") bomb test released energy approximately equal to . Nuclear bombs have had yields between 10 tons TNT (the W54) and 50 megatons for the Tsar Bomba (see TNT equivalent). A thermonuclear weapon weighing as little as can release energy equal to more than . A nuclear device no larger than a conventional bomb can devastate an entire city by blast, fire, and radiation. Since they are weapons of mass destruction, the proliferation of nuclear weapons is a focus of international relations policy. Nuclear weapons have been deployed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dnestr Radar
Dnestr radar (russian: Днестр) and Dnepr radar (russian: Днепр), both known by the NATO reporting name Hen House are the first generation of Soviet space surveillance and early warning radars. Six radars of this type were built around the periphery of the Soviet Union starting in the 1960s to provide ballistic missile warnings for attacks from different directions. They were the primary Soviet early warning radars for much of the later Cold War. In common with other Soviet and Russian early warning radars they are named after rivers, the Dnestr and the Dnepr. The Dnestr/Dnepr radars were intended to be replaced by the newer Daryal radars starting in the 1990s. Only two of the planned Daryal radars became operational, due to issues such as the dissolution of the Soviet Union. As of 2012, the Russian early warning network still consists of some radars of this vintage. It is likely that all the existing radars will be replaced by the third generation Voronezh radars b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early-warning Radar
An early-warning radar is any radar system used primarily for the long-range detection of its targets, i.e., allowing defences to be alerted as ''early'' as possible before the intruder reaches its target, giving the air defences the maximum time in which to operate. This contrasts with systems used primarily for tracking or gun laying, which tend to offer shorter ranges but offer much higher accuracy. EW radars tend to share a number of design features that improve their performance in the role. For instance, EW radar typically operates at lower frequencies, and thus longer wavelengths, than other types. This greatly reduces their interaction with rain and snow in the air, and therefore improves their performance in the long-range role where their coverage area will often include precipitation. This also has the side-effect of lowering their optical resolution, but this is not important in this role. Likewise, EW radars often use much lower pulse repetition frequency to maximi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AN/FPQ-16 PARCS
The AN/FPQ-16 Perimeter Acquisition Radar Attack Characterization System (PARCS or EPARCS) is a powerful United States Space Force phased-array radar system located in North Dakota. It is the second most powerful phased array radar system in the US Space Force's fleet of missile warning and space surveillance systems. PARCS was built by General Electric as the Perimeter Acquisition Radar (PAR), part of the US Army's Safeguard Program anti-ballistic missile system. PAR provided early warning of incoming ICBMs at ranges up to , feeding data to the interceptor station, equipped with a shorter-range radar. The PAR and other systems were collectively known as the Stanley R. Mickelsen Safeguard Complex. With the signing of the ABM Treaty in 1972, the U.S. was limited to a single ABM base protecting missile fields, and a second partially completed PAR in Montana was abandoned in-place. In 1975 the House Appropriations Committee voted to close Mickelsen and shut down Safeguard, whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LIM-49 Spartan
The LIM-49 Spartan was a United States Army anti-ballistic missile, designed to intercept attacking nuclear warheads from Intercontinental ballistic missiles at long range and while still outside the atmosphere. For actual deployment, a five-megaton thermonuclear warhead was planned to destroy the incoming ICBM warheads. It was part of the Safeguard Program. The Spartan was the latest and, as it turned out, final development in a long series of missile designs from the team of Bell Laboratories and Douglas Aircraft Company that started in the 1940s with the Nike. Spartan was developed directly from the preceding LIM-49 Nike Zeus, retaining the same tri-service identifier, but growing larger and longer ranged, from the Zeus' to approximately . The Spartan was superseded by the Nike-X project, later becoming the Sentinel Program. This was eventually cancelled and replaced with the much smaller Safeguard Program. Spartans were deployed as part of the Safeguard system from Octobe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nike-X
Nike-X was an anti-ballistic missile (ABM) system designed in the 1960s by the United States Army to protect major cities in the United States from attacks by the Soviet Union's intercontinental ballistic missile (ICBM) fleet during the Cold War. The X in the name referred to its experimental basis and was supposed to be replaced by a more appropriate name when the system was put into production. This never came to pass; in 1967 the Nike-X program was canceled and replaced by a much lighter defense system known as Sentinel. The Nike-X system was developed in response to limitations of the earlier Nike Zeus system. Zeus' radars could only track single targets, and it was calculated that a salvo of only four ICBMs would have a 90% chance of hitting a Zeus base. The attacker could also use radar reflectors or high-altitude nuclear explosions to obscure the warheads until they were too close to attack, making a single-warhead attack highly likely to succeed. Zeus would have been use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operation Dominic
Operation Dominic was a series of 31 nuclear test explosions with a total yield conducted in 1962 by the United States in the Pacific. This test series was scheduled quickly, in order to respond in kind to the Soviet resumption of testing after the tacit 1958–1961 test moratorium. Most of these shots were conducted with free-fall bombs dropped from B-52 bomber aircraft. Twenty of these shots were to test new weapons designs; six to test weapons effects; and several shots to confirm the reliability of existing weapons. The Thor missile was also used to lift warheads into near-space to conduct high-altitude nuclear explosion tests; these shots were collectively called Operation Fishbowl. Operation Dominic occurred during a period of high Cold War tension between the United States and the Soviet Union, since the Cuban Bay of Pigs Invasion had occurred not long before. Nikita Khrushchev announced the end of a three-year moratorium on nuclear testing on 30 August 1961, and Sovi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steradian
The steradian (symbol: sr) or square radian is the unit of solid angle in the International System of Units (SI). It is used in three-dimensional geometry, and is analogous to the radian, which quantifies planar angles. Whereas an angle in radians, projected onto a circle, gives a ''length'' on the circumference, a solid angle in steradians, projected onto a sphere, gives an ''area'' on the surface. The name is derived from the Greek 'solid' + radian. The steradian, like the radian, is a dimensionless unit, the quotient of the area subtended and the square of its distance from the centre. Both the numerator and denominator of this ratio have dimension length squared (i.e. , dimensionless). It is useful, however, to distinguish between dimensionless quantities of a different nature, so the symbol "sr" is used to indicate a solid angle. For example, radiant intensity can be measured in watts per steradian (W⋅sr−1). The steradian was formerly an SI supplementary unit, but this ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sprint (missile)
The Sprint was a two-stage, solid-fuel anti-ballistic missile (ABM), armed with a W66 enhanced-radiation thermonuclear warhead used by the United States Army from 1975-1976. It was designed to intercept incoming reentry vehicles (RV) after they had descended below an altitude of about , where the thickening air stripped away any decoys or radar reflectors and exposed the RV to observation by radar. As the RV would be traveling at about , Sprint had to have phenomenal performance to achieve an interception in the few seconds before the RV reached its target. Sprint accelerated at 100 ''g'', reaching a speed of in 5 seconds. Such a high velocity at relatively low altitudes created skin temperatures up to , requiring an ablative shield to dissipate the heat. The high temperature caused a plasma to form around the missile, requiring extremely powerful radio signals to reach it for guidance. The missile glowed bright white as it flew. Sprint was the centerpiece of the Nike-X sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Half-life
Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable atoms survive. The term is also used more generally to characterize any type of exponential (or, rarely, non-exponential) decay. For example, the medical sciences refer to the biological half-life of drugs and other chemicals in the human body. The converse of half-life (in exponential growth) is doubling time. The original term, ''half-life period'', dating to Ernest Rutherford's discovery of the principle in 1907, was shortened to ''half-life'' in the early 1950s. Rutherford applied the principle of a radioactive element's half-life in studies of age determination of rocks by measuring the decay period of radium to lead-206. Half-life is constant over the lifetime of an exponentially decaying quantity, and it is a characteristic unit for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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