Joe 4
Joe 4 was an American nickname for the first Soviet
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

 test of a thermonuclear weapon on August 12, 1953. It utilized a scheme in which fission and fusion fuel (lithium-6 deuteride) were "layered", a design known as the Sloika model in the Soviet Union. A ten-fold increase in explosive power was achieved by a combination of fusion energy and neutron-initiated ("boosted") fission. A similar design was earlier theorized by Edward Teller, but never tested, in the USA as the "Alarm Clock".

The Soviet thermonuclear weapons program initially researched two weapon designs. One design was the Sloika (RDS-6s), the other design was the Truba (RDS-6t). The RDS-6t was a two stage gun-type bomb with a deuterium
Deuterium, also called heavy hydrogen, is one of two stable isotopes of hydrogen. It has a natural abundance in Earth's oceans of about one atom in of hydrogen . Deuterium accounts for approximately 0.0156% of all naturally occurring hydrogen in Earth's oceans, while the most common isotope ...

Tritium is a radioactive isotope of hydrogen. The nucleus of tritium contains one proton and two neutrons, whereas the nucleus of protium contains one proton and no neutrons...

 secondary and was similar to the U.S. “classical Super” design. However, when the United States detonated a hydrogen bomb in the Pacific in 1952 (Ivy Mike
Operation Ivy
Operation Ivy was the eighth series of American nuclear tests, coming after Tumbler-Snapper and before Upshot-Knothole. Its purpose was to help upgrade the U.S. arsenal of nuclear weapons in response to the Soviet nuclear weapons program...

), higher priority was given to the RDS-6s design, which was considered to be more likely to work.

Joe 4 detonated with a force equivalent to 400 kilotons of TNT. The Soviet physicist Yuli Khariton estimated that Joe 4's yield was 15% to 20% fusion
Nuclear fusion
Nuclear fusion is the process by which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. This is usually accompanied by the release or absorption of large quantities of energy...

, the rest fission
Nuclear fission
In nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction in which the nucleus of an atom splits into smaller parts , often producing free neutrons and photons , and releasing a tremendous amount of energy...

 boosted by the fast neutrons released in the fusion. Being a single-stage weapon, though, it was not capable of being scaled up indefinitely like "true" hydrogen bombs (see Teller-Ulam design
Teller-Ulam design
The Teller–Ulam design is the nuclear weapon design concept used in most of the world's nuclear weapons. It is colloquially referred to as "the secret of the hydrogen bomb" because it employs hydrogen fusion, though in most applications the bulk of its destructive energy comes from uranium fission,...

 for more details on the distinctions between fusion weapons).

Despite its inability to be scaled into the megaton range, the detonation was used by Soviet diplomats as leverage. The Soviets claimed that they too had a hydrogen bomb, but unlike the United States' first thermonuclear weapon, theirs was deployable (i.e. could be dropped from a bomber). Despite this claim, U.S. experts disputed its standing as a "true" hydrogen bomb. The United States did not develop a deployable version of its hydrogen bomb until 1954. The Sloika model was never widely deployed.

The first Soviet test of a "true" hydrogen bomb was on November 22, 1955, the RDS-37
RDS-37 was the Soviet Union's first "true" hydrogen bomb, first tested on November 22, 1955. The weapon had a nominal yield of approximately 3 megatons. It was scaled down to 1.6 megatons for the live test....

 warhead. All were at Semipalatinsk Test Site
Semipalatinsk Test Site
The Semipalatinsk Test Site was the primary testing venue for the Soviet Union's nuclear weapons. It is located on the steppe in northeast Kazakhstan , south of the valley of the Irtysh River...

, Kazakhstan
Kazakhstan , officially the Republic of Kazakhstan, is a transcontinental country in Central Asia and Eastern Europe. Ranked as the ninth largest country in the world, it is also the world's largest landlocked country; its territory of is greater than Western Europe...

. Like RDS-6, it was a "dry" weapon, using lithium-6 deuteride instead of liquid hydrogen.

See also

  • Joe 1
    Joe 1
    The RDS-1 , also known as First Lightning , was the Soviet Union's first nuclear weapon test. In the west, it was code-named Joe-1, in reference to Joseph Stalin. It was test-exploded on 29 August 1949, at Semipalatinsk, Kazakh SSR, after a top-secret R&D project...

  • RDS-37
    RDS-37 was the Soviet Union's first "true" hydrogen bomb, first tested on November 22, 1955. The weapon had a nominal yield of approximately 3 megatons. It was scaled down to 1.6 megatons for the live test....

  • Soviet atomic bomb project
    Soviet atomic bomb project
    The Soviet project to develop an atomic bomb , was a clandestine research and development program began during and post-World War II, in the wake of the Soviet Union's discovery of the United States' nuclear project...

  • Ivy Mike
    Ivy Mike
    Ivy Mike was the codename given to the first United States test of a thermonuclear weapon, in which a major part of the explosive yield came from nuclear fusion. It was detonated on November 1, 1952 by the United States at on Enewetak, an atoll in the Pacific Ocean, as part of Operation Ivy...

  • Castle Bravo
    Castle Bravo
    Castle Bravo was the code name given to the first U.S. test of a dry fuel thermonuclear hydrogen bomb device, detonated on March 1, 1954 at Bikini Atoll, Marshall Islands, as the first test of Operation Castle. Castle Bravo was the most powerful nuclear device ever detonated by the United States ,...

  • Boosted fission weapon
    Boosted fission weapon
    A boosted fission weapon usually refers to a type of nuclear bomb that uses a small amount of fusion fuel to increase the rate, and thus yield, of a fission reaction. The neutrons released by the fusion reactions add to the neutrons released in the fission, as well as inducing the fission reactions...

External links

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