Tsar Bomba (Царь-бомба, literally "King Bomb") is the Western name for the RDS-220 hydrogen bomb (codenamed "Иван" (Ivan) by its developers) — the largest, most powerful nuclear weapon ever detonated. Developed by the Soviet Union, the bomb was originally designed to have a yield of about 100 megatons of TNT; however that was reduced by half in order to limit the amount of nuclear fallout that would result. Two bombs were built, a mock bomb and the real bomb, with the real bomb being tested on October 30, 1961, in the Novaya Zemlya archipelago. Despite testing, the weapon never entered service; it was simply a demonstration of the capabilities of the Soviet Union's military technology at that time. The mock bomb was stored in the Russian Nuclear Weapons Museum in Sarov.

Design

The Tsar Bomba was a three-stage hydrogen bomb with a yield of about 50 megatons. This is equivalent to ten times the amount of all the explosives used in World War II combined. A three-stage H-bomb uses a fission bomb primary to compress a thermonuclear secondary, as in most H-bombs, and then uses energy from the resulting explosion to compress a much larger additional thermonuclear stage. However, there is evidence that the Tsar Bomba had a number of third stages rather than a single very large one.

The initial three stage design was capable of approximately 100 Mt (Megatons), but at a cost of too much radioactive fallout. To limit fallout, the third stage, and possibly the second stage, had a lead tamper instead of a uranium-238 fusion tamper (which greatly amplifies the reaction by fissioning uranium atoms with fast neutrons from the fusion reaction). This eliminated fast fission by the fusion-stage neutrons, so that approximately 97% of the total energy resulted from fusion alone (as such, it was one of the "cleanest" nuclear bombs ever created, generating a very low amount of fallout relative to its yield). There was a strong incentive for this modification since most of the fallout from a test of the bomb would fall on populated Soviet territory.

The components were designed by a team of physicists which was headed by Academician Julii Borisovich Khariton and included Andrei Sakharov, Victor Adamsky, Yuri Babayev, Yuri Smirnov, and Yuri Trutnev. Shortly after the Tsar Bomba was detonated, Sakharov began speaking out against nuclear weapons, which culminated in his becoming a dissident.