IVY MIKE

'Ivy Mike' was the code name given to the first (successful) 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 11.6709 N, 162.1980 E 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. This device was also known as a Super bomb.
Due to its physical size and fusion fuel type (cryogenic liquid deuterium) the Mike device was not suitable for use as a thermonuclear weapon. 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.

Contents

Device design and preparations

Detonation

See also

External links

References

Device design and preparations

The "Mike" device was essentially a 62 ton building that resembled a factory rather than a weapon. At its centre, a very large cylindrical thermos flask or cryostat, held the cryogenic deuterium fusion fuel. A regular fission bomb (the "primary") at one end was used to create the conditions needed to initiate the fusion reaction.
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 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 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 60 tons (54 tonnes).
The entire Mike device (including cryogenic equipment) weighed 82 tons (73.8 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 (2.743 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 needed for the test.

Detonation

The test was carried out at 0715 local time on November 1, 1952; it produced a yield of 10.4 megatons. However, 77% of the final yield came from fast fission of the uranium tamper, which meant that the device produced large amounts of fallout.
The fireball was over 3 miles (5 km) wide, and the mushroom cloud rose to an altitude of 57,000 feet (17.0 km) in less than 90 seconds. One minute later it had reached 108,000 feet (33.0 km), before stabilizing at 120,000 feet (37.0 km) with the top eventually spreading out to a diameter of 100 miles (161 km) with a stem 20 miles (32 km) wide.
The blast created a crater 6,240 feet (1.9 km) in diameter and 164 feet (50 m) deep where Elugelab had once been; the blast and water waves from the explosion (some waves up to twenty feet high) stripped the test islands clean of vegetation, as observed by a helicopter survey within 60 minutes after the test, by which time the mushroom cloud and steam had been blown away. Irradiated coral debris fell upon ships stationed 30 miles (48 km) from the blast, and the immediate area around the atoll was heavily contaminated for some time.
The entire shot was documented by the filmmakers of Lookout Mountain studios. The film was accompanied by powerful, Wagner-esque music featured on many test films of that period and was hosted by actor Reed Hadley. After the test a private screening was given to President Dwight D. Eisenhower. It was later released to the public after censoring, and was for many days played continually on many television channels.
Edward Teller, who was perhaps the most ardent supporter of the development of the hydrogen bomb, was in Berkeley, California at the time of the shot. He was able to receive first notice that the test was successful by observing a seismometer, which picked up the shock wave travelling through the earth all the way from the South Pacific test site. (Rhodes, ''Dark Sun'')
In his later memoirs, Teller wrote that he immediately sent a telegram to atomic physicist and long-time rival, Robert Oppenheimer, following the detonation. It simply contained the words "It's a boy". Oppenheimer had been an outspoken critic of the Super test prior to Ivy Mike's detonation.
The test took the world into the thermonuclear era.

See also

★ History of nuclear weapons

★ Ivy King

★ Operation Castle

★ Mike Fireball

External links

★ Downloadable/Streamable Declassified Film: Operation IVY (1 hour originally Secret version, 1953) at the Internet Archive

★ Operation Ivy film (27 minutes unclassified civil defence version, 1953)

★ Operation Ivy

★ Video of the 'Ivy Mike test'

References

★ Chuck Hansen, ''U. S. Nuclear Weapons: The Secret History'' (Arlington: AeroFax, 1988)

★ Richard Rhodes, ''Dark Sun: The Making of the Hydrogen Bomb'' (New York: Simon and Schuster, 1995)