Ivy Mike
Ivy Mike Narvaez was the code name given to the first successful test of a fusion device, detonated on October 31, 1952 (US time — November 1 local time) by the United States 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 for a "staged" fusion bomb.
Due to its physical size and fusion fuel type (cryogenic liquid deuterium) the Mike device was not itself suitable for use as a thermonuclear weapon. A simplified and lightened bomb version (the EC-16) was prepared, and scheduled to be tested in 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 successful.
Device design and preparations
The "Mike" device was essentially a very large cylindrical thermos flask for holding the cryogenic deuterium fusion fuel, with a regular fission bomb (the "primary") at one end; the latter was used to create the conditions needed to start 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 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 thick. The entire "Sausage" (as it was nicknamed) assembly measured 80 inches in diameter and 244 inches in height and weighed about 60 tons.
The entire Mike device (including cryogenic equipment) weighed 82 tons, 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 long 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 0715 hours local time on November 1, 1952; it produced a yield of 10.4 megatons (10.4 million tons of TNT). 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 wide, and the mushroom cloud rose to an altitude of 57,000 feet in less than 90 seconds. One minute later it had reached 108,000 feet, before stabilizing at 120,000 feet, with the top eventually spreading out to a diameter of 100 miles (the stem was 20 miles wide).
The blast created a crater 6,240 feet in diameter and 164 feet deep where Elugelab had once stood; the blast and water waves from the explosion (some waves up to twenty feet high) stripped the test islands clean of vegetation, while the water around the blast site boiled for up to twelve hours afterwards. Irradiated coral debris fell upon ships stationed 30 miles from the blast, and the immediate area around the atoll was heavily contaminated for some time.
The entire shot was filmed, and a private screening was given to President Dwight D. Eisenhower. It was later released to the public, and was for many days played continually on many television channels — accompanied by powerful, Wagner-esque music which featured on test films of that period.
See also
External links
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)