Ivy Mike is the codename given to the first of two nuclear weapon tests done by the United States under Project Ivy in 1952, in the Pacific Proving Grounds which includes some of the Marshall Islands and a few other scattered sites located in the Pacific Ocean.
It was the first ever detonation of a two-stage thermonuclear weapon; what is now commonly known as the 'hydrogen bomb' as opposed to the pure fission 'atomic bombs' which were dropped on Hiroshima and Nagasaki , Japan in 1945.
The difference between the two lies in the nature of the process that occurs at the atomic level in order to create an explosion. The first nuclear weapons, atomic bombs, were created just by fission reactions. Ivy Mike's power came from a fusion reaction triggered by a fission reaction.
Fission is a process in which an atom's nucleus is split into lighter, smaller parts and free neutrons and photons are released as gamma rays.
Fusion is the process by which two or more atoms' nuclei fuse together and form a single nucleus that is heavier than the original nuclei. This process is continually taking place in our sun, as hydrogen atoms are fused into helium atoms. As the lightest known element, Hydrogen is first in the periodic table of elements and Helium is second.
Although the details remain forever highly classified, it is believed that the secondary fusion reaction in Ivy Mike was triggered by an initial fission implosion which compressed the second payload with the x-rays that the fission reaction generated. This in turn caused the fusion reaction in the secondary part of the bomb. The second reaction is much more powerful than the initial triggering reaction and results in a far greater energy release than a pure fission device alone. For this reason it has become the standard design for nuclear weapons developed in the 5 nuclear states signatory to the NPT.
Nuclear reactions are generally about a million times more powerful than comparable chemical reactions; that is, a nuclear explosion releases about a million times more energy than its chemical equivalent.
Ivy Mike's detonation produced an energetic yield of around 10 to 12 megatons. A megaton is a measurement used to describe explosive energy and is equal to the amount of energy released by 1 ton of TNT. It was nearly 500 times more powerful than the bomb dropped on Nagasaki.
Ivy Mike was not a bomb proper, due to size and other constraints, but was built within a structure on Elugelab island in the Enewetak atoll.
After the mushroom cloud cleared, Elugelab island was no longer there. All that remained was a large underwater pit.
