Hydrogen bomb

The invention: Popularly known as the “H-Bomb,” the hydrogen
bomb differs from the original atomic bomb in using fusion,
rather than fission, to create a thermonuclear explosion almost a
thousand times more powerful.
The people behind the invention:
Edward Teller (1908- ), a Hungarian-born theoretical
physicist
Stanislaw Ulam (1909-1984), a Polish-born mathematician
Crash Development
Afew months before the 1942 creation of the Manhattan Project,
the United States-led effort to build the atomic (fission) bomb, physicist
Enrico Fermi suggested to Edward Teller that such a bomb
could release more energy by the process of heating a mass of the
hydrogen isotope deuterium and igniting the fusion of hydrogen
into helium. Fusion is the process whereby two atoms come together
to form a larger atom, and this process usually occurs only in stars,
such as the Sun. Physicists Hans Bethe, George Gamow, and Teller
had been studying fusion since 1934 and knew of the tremendous
energy than could be released by this process—even more energy
than the fission (atom-splitting) process that would create the atomic
bomb. Initially, Teller dismissed Fermi’s idea, but later in 1942, in
collaboration with Emil Konopinski, he concluded that a hydrogen
bomb, or superbomb, could be made.
For practical considerations, it was decided that the design of the
superbomb would have to wait until after the war. In 1946, a secret
conference on the superbomb was held in Los Alamos, New Mexico,
that was attended by, among other Manhattan Project veterans,
Stanislaw Ulam and Klaus Emil Julius Fuchs. Supporting the investigation
of Teller’s concept, the conferees requested a more complete
mathematical analysis of his own admittedly crude calculations
on the dynamics of the fusion reaction. In 1947, Teller believed
that these calculations might take years. Two years later, however,the Soviet explosion of an atomic bomb convinced Teller that America’s
ColdWar adversary was hard at work on its own superbomb.
Even when new calculations cast further doubt on his designs,
Teller began a vigorous campaign for crash development of the hydrogen
bomb, or H-bomb.
The Superbomb
Scientists knew that fusion reactions could be induced by the explosion
of an atomic bomb. The basic problem was simple and formidable:
How could fusion fuel be heated and compressed long
enough to achieve significant thermonuclear burning before the
atomic fission explosion blew the assembly apart? A major part of
the solution came from Ulam in 1951. He proposed using the energy
from an exploding atomic bomb to induce significant thermonuclear
reactions in adjacent fusion fuel components.
This arrangement, in which the A-bomb (the primary) is physically
separated from the H-bomb’s (the secondary’s) fusion fuel, became
known as the “Teller-Ulam configuration.” All H-bombs are
cylindrical, with an atomic device at one end and the other components
filling the remaining space. Energy from the exploding primary
could be transported by X rays and would therefore affect the
fusion fuel at near light speed—before the arrival of the explosion.
Frederick de Hoffman’s work verified and enriched the new concept.
In the revised method, moderated X rays from the primary irradiate
a reactive plastic medium surrounding concentric and generally
cylindrical layers of fusion and fission fuel in the secondary.
Instantly, the plastic becomes a hot plasma that compresses and
heats the inner layer of fusion fuel, which in turn compresses a central
core of fissile plutonium to supercriticality. Thus compressed,
and bombarded by fusion-produced, high-energy neutrons, the fission
element expands rapidly in a chain reaction from the inside
out, further compressing and heating the surrounding fusion fuel,
releasing more energy and more neutrons that induce fission in a
fuel casing-tamper made of normally stable uranium 238.
With its equipment to refrigerate the hydrogen isotopes, the device
created to test Teller’s new concept weighed more than sixty
tons. During Operation Ivy, it was tested at Elugelab in the Marshall Islands on November 1, 1952. Exceeding the expectations of all concerned
and vaporizing the island, the explosion equaled 10.4 million
tons of trinitrotoluene (TNT), which meant that it was about
seven hundred times more powerful than the atomic bomb dropped
on Hiroshima, Japan, in 1945. A version of this device weighing
about 20 tons was prepared for delivery by specially modified Air
Force B-36 bombers in the event of an emergency during wartime.
In development at Los Alamos before the 1952 test was a device
weighing only about 4 tons, a “dry bomb” that did not require refrigeration
equipment or liquid fusion fuel; when sufficiently compressed
and heated in its molded-powder form, the new fusion fuel
component, lithium-6 deutride, instantly produced tritium, an isotope
of hydrogen. This concept was tested during Operation Castle
at Bikini atoll in 1954 and produced a yield of 15 million tons of TNT,
the largest-ever nuclear explosion created by the United States.
Consequences
Teller was not alone in believing that the world could produce
thermonuclear devices capable of causing great destruction. Months
before Fermi suggested to Teller the possibility of explosive thermonuclear
reactions on Earth, Japanese physicist Tokutaro Hagiwara
had proposed that a uranium 235 bomb could ignite significant fusion
reactions in hydrogen. The Soviet Union successfully tested an
H-bomb dropped from an airplane in 1955, one year before the
United States did so.
Teller became the scientific adviser on nuclear affairs of many
presidents, from Dwight D. Eisenhower to Ronald Reagan. The
widespread blast and fallout effects of H-bombs assured the mutual
destruction of the users of such weapons. During the Cold War
(from about 1947 to 1981), both the United States and the Soviet
Union possessed H-bombs. “Testing” these bombs made each side
aware of how powerful the other side was. Everyone wanted to
avoid nuclear war. It was thought that no one would try to start a
war that would end in the world’s destruction. This theory was
called deterrence: The United States wanted to let the Soviet Union
know that it had just as many bombs, or more, than it did, so that the
leaders of the Sovet Union would be deterred from starting a war.Teller knew that the availability of H-bombs on both sides was
not enough to guarantee that such weapons would never be used. It
was also necessary to make the Soviet Union aware of the existence
of the bombs through testing. He consistently advised against U.S.
participation with the Soviet Union in a moratorium (period of
waiting) on nuclear weapons testing. Largely based on Teller’s urging
that underground testing be continued, the United States rejected
a total moratorium in favor of the 1963 Atmospheric Test Ban
Treaty.
During the 1980’s, Teller, among others, convinced President
Reagan to embrace the Strategic Defense Initiative (SDI). Teller argued
that SDI components, such as the space-based “Excalibur,” a
nuclear bomb-powered X-ray laser weapon proposed by the Lawrence-
Livermore National Laboratory, would make thermonuclear
war not unimaginable, but theoretically impossible.