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Ivy Mike
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Ivy Mike was the codename given to the first US test of a fusion device where a major part of the explosive yield came from fusion. It was detonated on November 1, 1952 by the United States at on Enewetak, an atoll in the Pacific Ocean, as part of Operation Ivy. The device was the first full test of the Teller-Ulam design, a staged fusion bomb, and is generally considered the first successful test of a hydrogen bomb.
Due to its physical size and fusion fuel type (cryogenic liquid deuterium–tritium) the Mike device was not suitable for use as a thermonuclear weapon; it was intended as an extremely conservative experiment to validate the concepts used for multi-megaton detonations.
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Encyclopedia
Ivy Mike was the codename given to the first US test of a fusion device where a major part of the explosive yield came from fusion. It was detonated on November 1, 1952 by the United States at on Enewetak, an atoll in the Pacific Ocean, as part of Operation Ivy. The device was the first full test of the Teller-Ulam design, a staged fusion bomb, and is generally considered the first successful test of a hydrogen bomb.
Due to its physical size and fusion fuel type (cryogenic liquid deuterium–tritium) the Mike device was not suitable for use as a thermonuclear weapon; it was intended as an extremely conservative experiment to validate the concepts used for multi-megaton detonations. A simplified and lightened bomb version (the EC-16) was prepared, and scheduled to be tested in operation Castle Yankee, as a backup in case the non-cryogenic "Shrimp" fusion device (tested in Castle Bravo) failed to work; that test was cancelled when the Bravo device was tested successfully, making the cryogenic designs obsolete.
Device Design and Preparations
The "John", a 62 ton device, was essentially a building that resembled a factory rather than a weapon. It has been reported that Russian engineers derisively referred to Mike as a "thermonuclear installation". At its center, a very large cylindrical thermos flask or cryostat, held the cryogenic deuterium–tritium fusion fuel. A regular fission bomb (the "primary") at one end was used to create the conditions needed to initiate the fusion reaction.
The device was designed by Richard Garwin, a student of Enrico Fermi, on the suggestion of Edward Teller. It had been decided that nothing other than a full-scale test would validate the idea of the Teller-Ulam design, and Garwin was instructed to use very conservative estimates when designing the test, and that it need not be deployable. (That is, it need not be small, light, and sturdy enough to be carried by an airplane and dropped on a target.)
The primary stage was a TX-5 boosted fission bomb in a separate space atop the assembly (so it would not freeze, rendering it inoperable). The "secondary" fusion stage used liquid deuterium–tritium despite the difficulty of handling this material, because this fuel simplified the experiment, and made the results easier to analyze. Running down the center of the flask which held it was a cylindrical rod of plutonium (the "sparkplug") to ignite the fusion reaction. Surrounding this assembly was a five-ton (4.5 tonne) natural uranium "tamper". The interior of the tamper was lined with sheets of lead and polyethylene foam, which formed a radiation channel to conduct X-rays from the primary to secondary. (The function of X-rays was to hydrodynamically compress the secondary, increasing the density and temperature of the deuterium–tritium to the levels needed to sustain the thermonuclear reaction, and compressing the sparkplug to supercriticality ignition.) The outermost layer was a steel casing 10-12 inches (25-30 cm) thick. The entire assembly, nicknamed "Sausage", measured 80 inches (2.03 m) in diameter and 244 inches (6.19 m) in height and weighed about 54 tons.
The entire Mike device (including cryogenic equipment) weighed 82 short tons (73.8 metric tonnes), and was housed in a large corrugated-aluminium building called a "shot cab" which was set up on the Pacific island of Elugelab, part of the Enewetak atoll.
A 9,000-foot (2.7 km) artificial causeway connected the islands of Elugelab, Teiter, Bogairikk, and Bogon. Atop this causeway was an aluminium-sheathed plywood tube (named a "Krause-Ogle box") filled with helium ballonets. This allowed gamma and neutron radiation to pass uninhibited to an unmanned detection station housed in a bunker on Bogon.
In total, 9,350 military and 2,300 civilian personnel were involved in the Mike shot. A large cryogenics plant was installed on Parry Island, at the South end of the Eniwetak atoll, to produce the liquid hydrogen (used for cooling the device) and deuterium–tritium needed for the test.
Detonation
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