Definition for Hydrogen Bomb
From Biology Forums Dictionary
A hydrogen bomb is, by far, the most destructive weapon that mankind has ever invented. It is the most powerful type of nuclear bomb, as much as 25,000 times the yield of the nuclear bombs dropped on Hiroshima and Nagasaki, Japan. Unlike conventional atom bombs (also known as A-bombs), which release energy by fissioning (breaking apart) heavy atomic nuclei like uranium and plutonium, a hydrogen bomb releases energy by fusing together light nuclei like tritium or deuterium, converting even more matter into energy. When Truman authorized the dropping of the A-bomb on Hiroshima and Nagasaki, he said that the weapons used the same power that the Sun did, but that wasn't actually true -- the Sun uses nuclear fusion, not nuclear fission. Thus, a hydrogen bomb really does release the power that fuels the Sun.
The largest nuclear bombs, and the backbone of the nuclear arsenal of the United States and Russia, are hydrogen bombs. These bombs work using a two-stage design whereby a fission bomb "primary" is detonated using the conventional implosion method, which then compresses a fusion fuel "secondary" and ignites a uranium "spark plug" which fissions and subjects the fusion fuel to the heat necessary to begin a chain reaction -- about 20 million degrees F. The light nuclei fuse together into heavier elements, releasing tremendous energy from the strong nuclear force that binds their constituent particles together.
As a result of using fusion rather than fission, the bomb yield is much higher. In fission bombs, approximately 0.1% of the mass of the fuel is converted directly into energy, while in fusion bombs, this ratio is slightly improved, on the order of 0.3%. The first time the principle of a hydrogen bomb was tested was on 9 May 1951 by the United States military, during the George shot of Operation Greenhouse at the Pacific Proving Grounds. Most of the yield of this test came from fission fuel, but it tested the idea that a fission bomb could be used as a stepping stone to something even more destructive. A similar test, Item, took place on 25 May 1951.
The first true hydrogen bomb test, Ivy Mike, was on 1 November 1952, detonated at Enewetak Atoll in the Pacific, as part of Operation Ivy. The bomb exploded with a force equivalent to 10.4 megatons of TNT (over 450 times more powerful than the atomic bomb dropped on Nagasaki during WWII). Using liquid deuterium as fuel, this hydrogen bomb required 18 tonnes of refrigeration equipment to keep the deuterium in liquid form. A later test, Castle Bravo, used solid lithium deuteride instead, decreasing the weight of the device and making it a practical weapon. The Castle Bravo shot is the most powerful nuclear weapon ever tested by the United States, with a yield of 15 megatons.
Today, all of humanity is still put at risk by a nuclear winter initiated by hydrogen bombs.
