HYDROGEN BOMB
Will man eventually destroy civilization?
Hydrogen bomb or H-bomb, derives a large portion
of its energy from the nuclear fusion of hydrogen isotopes.
In an atomic bomb, uranium or plutonium is split into lighter
elements that together weigh less than the original atoms,
the remainder of the mass appearing as energy. Unlike this
fission bomb, the hydrogen bomb functions by the fusion, or
joining together, of lighter elements into heavier elements.
The end product again weighs less than its components, the
difference once more appearing as energy. Because extremely
high temperatures are required in order to initiate fusion
reactions, the hydrogen bomb is also known as a thermonuclear
bomb.
The first thermonuclear bomb was exploded in
1952 at Enewetak by the United States, the second in 1953
by Russia (then the USSR). Great Britain, France, and China
have also exploded thermonuclear bombs, and these five nations
comprise the so-called nuclear club-nations that have the
capability to produce nuclear weapons and admit to maintaining
an inventory of them. The three smaller Soviet successor states
that inherited nuclear arsenals (Ukraine, Kazakhstan, and
Belarus) relinquished all nuclear warheads, which have been
removed to Russia. Several other nations either have tested
thermonuclear devices or claim to have the capability to produce
them, but officially state that they do not maintain a stockpile
of such weapons; among these are India, Israel, and Pakistan.
South Africa's apartheid regime built six nuclear bombs but
dismantled them later.
The presumable structure of a thermonuclear
bomb is as follows: at its center is an atomic bomb; surrounding
it is a layer of lithium deuteride (a compound of lithium
and deuterium, the isotope of hydrogen with mass number 2);
around it is a tamper, a thick outer layer, frequently of
fissionable material, that holds the contents together in
order to obtain a larger explosion. Neutrons from the atomic
explosion cause the lithium to fission into helium, tritium
(the isotope of hydrogen with mass number 3), and energy.
The atomic explosion also supplies the temperatures needed
for the subsequent fusion of deuterium with tritium, and of
tritium with tritium (50,000,000°C and 400,000,000°C,
respectively). Enough neutrons are produced in the fusion
reactions to produce further fission in the core and to initiate
fission in the tamper.
Since the fusion reaction produces mostly neutrons
and very little that is radioactive, the concept of a "clean"
bomb has resulted: one having a small atomic trigger, a less
fissionable tamper, and therefore less radioactive fallout.
Carrying this progression further would result in the suggested
neutron bomb, which would have a minimum trigger and a nonfissionable
tamper; there would be blast effects and a hail of lethal
neutrons but almost no radioactive fallout; this theoretically
would cause minimal physical damage to buildings and equipment
but kill most living things. The theorized cobalt bomb is,
on the contrary, a radioactively "dirty" bomb having
a cobalt tamper. Instead of generating additional explosive
force from fission of the uranium, the cobalt is transmuted
into cobalt-60, which has a half-life of 5.26 years and produces
energetic (and thus penetrating) gamma rays. The half-life
of Co-60 is just long enough so that airborne particles will
settle and coat the earth's surface before significant decay
has occurred, thus making it impractical to hide in shelters.
This prompted physicist Leo Szilard to call it a "doomsday
device" since it was capable of wiping out life on earth.
Hydrogen Bomb, Ctsy: USAF
Hydrogen Bomb, Ctsy: USAF
Like other types of nuclear explosion, the explosion
of a hydrogen bomb creates an extremely hot zone near its
center. In this zone, because of the high temperature, nearly
all of the matter present is vaporized to form a gas at extremely
high pressure. A sudden overpressure, i.e., a pressure far
in excess of atmospheric pressure, propagates away from the
center of the explosion as a shock wave, decreasing in strength
as it travels. It is this wave, containing most of the energy
released that is responsible for the major part of the destructive
mechanical effects of a nuclear explosion. The details of
shock wave propagation and its effects vary depending on whether
the burst is in the air, underwater, or underground.
Source: Columbia Encyclopedia
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