A History of Research and a Review of Recent Developments

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The nature of explosions
ogive, an electronic assembly, a power-supply assembly, a liquid crystal display
assembly, and a safety and arming device. Once the weapon is fired, the
electronic assembly senses continuous spin above a designated speed in
revolutions per minute, and then initiates the fusing operations. These consist
of the activation of the safety and arming device which makes the fuse ready
to function upon target impact. When the fuse functions the explosive in the
projectile detonates. Electronic technology has now advanced to allow the
fitting of a proximity fuse within the same standard configuration, so that an
electromagnetic signal is generated which reflects off the target area to initiate
detonation at a specific height above the target.
There are numerous technical exploration programmes to improve the
electronic fusing of all types of missile warheads. The problems of early detonation
or battery failure, the consistency of burst height, rain sensitivity, and vulnerability
to electromagnetic effects are all areas where the research level is high. The type
of target is an important factor. Urban targets such as triple brickwork and
concrete bunkers need different delay, proximity and time characteristics in
fuses than shipboard armour penetration. The search continues for effective
multi-option fuses that can be normally or inductively set and used for a range
of targets and a range of weapons, projectiles and propelling systems.
1.2 NUCLEAR EXPLOSIONS
At about the time the development of TNT as a high explosive began, the
French physicist H.A.Becquerel noticed in 1896 that uranium emitted unusual
radiations, an observation of great significance that came as a consequence of
the discovery a few months earlier of X-rays by W.K.Röntgen, professor of
physics in the University of Wurzburg, Bavaria. Becquerel’s original investigations
on the photographic effects of penetrating radiation were quickly taken up, the
science of radioactivity was established, and by 1899 the New Zealand-born
scientist Ernest Rutherford had shown that the radiation from uranium was a
complex matter, involving easily absorbed radiation (a rays), and more penetrating
radiation (ß rays). Later the extremely penetrating γ rays were discovered.
The particles were used by Rutherford to explore atoms over a period of
many years, and in 1919 he observed that nitrogen, when bombarded by particles
emitted the nucleus of the hydrogen atom. This nucleus became known as a
proton, and with its emission the atom had been smashed. More nuclear
transformations were discovered by J.Chadwick in 1932, when he recorded the
neutron, capable of freely penetrating many centimetres of material. His work
was taken forward, and the utilization of nuclear energy on a large scale was
made possible just before the Second World War when the scientists Hahn and
Strassmann from Berlin discovered uranium fission. The impinging of neutrons
on the uranium nucleus produced a number of radioactive substances because
the nucleus was on the verge of disintegration before the bombardment began.
The breaking up of the nucleus was named the fission, and in 1939 Szilard,