An explosive booster is a sensitive explosive charge that acts as a bridge between a (relatively weak) conventional detonator and a low-sensitivity (but typically high-energy) explosive such as TNT. By itself, the initiating detonator would not deliver sufficient energy to set off the low-sensitivity charge. However, it detonates the primary charge (the booster), which then delivers an explosive shockwave that is sufficient to detonate the secondary, main, high-energy charge.
Unlike C4plastic explosive, not all explosives can be detonated simply by inserting a detonator and firing it.
An initiator such as a shock tube, cannon fuse, or even a conventional detonator does not deliver a sufficient shock to detonate charges comprising TNT, Composition B, ANFO and many other high explosives. Therefore, some form of "booster" is required to amplify the energy released by the detonator so that the main charge will detonate.
At first, picric acid was used as a booster to detonate TNT, though it was superseded due to the inherent danger of picrate formation. Tetryl replaced picric acid because it is more stable, and was once a very popular chemical for booster charges, particularly during World War II. However, since then, tetryl has largely been replaced by other compositions, e.g. a small cylinder or pellet of phlegmatizedRDX (e.g. CH-6 or Composition A-5) or PETN (slightly larger than the actual detonator) into which the detonator itself is inserted.
When encountered in connection with artillery shells or air-dropped bombs, a booster charge is sometimes referred to as the "gaine", from French: gaine-relais. See detonators.
At a purely technical level, a sufficiently large detonator would initiate high explosives without the need for a booster charge. However, there are very good reasons why this method is never used. Firstly, there is a major safety issue, i.e. detonators are (like all primary explosives) much more sensitive to shock, heat, and friction than an explosive booster. Therefore, minimizing the amount of primary explosives that users must store or carry greatly reduces the likelihood of serious accidents. An additional economic reason for using explosive booster charges is that chemical compounds used in detonators (e.g. lead styphnate) are comparatively expensive to produce and encapsulate when compared to the manufacturing costs of explosive boosters.
A common form for boosters is to cast the explosive material into a cylindrical shell made of cardboard or plastic; these are accordingly known as cast boosters.
Gallery
Cross-sectional view of an M4 mine showing the detonator and adjacent booster charge surrounded by the main explosive charge of TNT
Cut-away view of an M14 antipersonnel landmine. No booster is required because the main explosive filling is tetryl, which is sufficiently sensitive to be initiated by the detonator alone
Cut-away view of an RPG-2 rocket grenade showing booster charge
Cut-away view of a M2 mine showing booster charge above detonator
A group of 105mm artillery shells with plastic explosive stuffed into their fuze pockets to act as booster charges. Each of the five shells has been linked together with red detcord to make them detonate simultaneously. To turn this assembly into a booby trap, the final step would be to connect an M142 firing device to the detcord and hide everything under some form of cover e.g. newspapers or a bed-sheet.
Related Research Articles
An explosive is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An explosive charge is a measured quantity of explosive material, which may either be composed solely of one ingredient or be a mixture containing at least two substances.
Trinitrotoluene, more commonly known as TNT (and more specifically 2,4,6-trinitrotoluene, and by its preferred IUPAC name 2-methyl-1,3,5-trinitrobenzene), is a chemical compound with the formula C6H2(NO2)3CH3. TNT is occasionally used as a reagent in chemical synthesis, but it is best known as an explosive material with convenient handling properties. The explosive yield of TNT is considered to be the standard comparative convention of bombs and asteroid impacts. In chemistry, TNT is used to generate charge transfer salts.
Pentaerythritol tetranitrate (PETN), also known as PENT, pentyl, PENTA, TEN, corpent, or penthrite, is an explosive material. It is the nitrate ester of pentaerythritol, and is structurally very similar to nitroglycerin. Penta refers to the five carbon atoms of the neopentane skeleton. PETN is a very powerful explosive material with a relative effectiveness factor of 1.66. When mixed with a plasticizer, PETN forms a plastic explosive. Along with RDX it is the main ingredient of Semtex.
2,4,6-Trinitrophenylmethylnitramine or tetryl (C7H5N5O8) is an explosive compound used to make detonators and explosive booster charges.
A detonator is a device used to make an explosive or explosive device explode. Detonators come in a variety of types, depending on how they are initiated and details of their inner working, which often involve several stages. Types of detonators include non-electric and electric. Non-electric detonators are typically stab or pyrotechnic while electric are typically "hot wire", exploding bridge wire or explosive foil.
The percussion cap, percussion primer, or caplock, introduced in the early 1820s, is a type of single-use percussion ignition device for muzzle loader firearm locks enabling them to fire reliably in any weather condition. Its invention gave rise to the caplock mechanism or percussion lock system which used percussion caps struck by the hammer to set off the gunpowder charge in rifles and cap and ball firearms. Any firearm using a caplock mechanism is a percussion gun. Any long gun with a cap-lock mechanism and rifled barrel is a percussion rifle. Cap and ball describes cap-lock firearms discharging a single bore-diameter spherical bullet with each shot.
C-4 or Composition C-4 is a common variety of the plastic explosive family known as Composition C, which uses RDX as its explosive agent. C-4 is composed of explosives, plastic binder, plasticizer to make it malleable, and usually a marker or odorizing taggant chemical. C-4 has a texture similar to modelling clay and can be molded into any desired shape. C-4 is relatively insensitive and can be detonated only by the shock wave from a detonator or blasting cap.
A shell, in a modern military context, is a projectile whose payload contains an explosive, incendiary, or other chemical filling. Originally it was called a bombshell, contrasting with solid shells used for early rifled artillery, but "shell" has come to be unambiguous in a military context. A shell can hold a tracer.
The exploding-bridgewire detonator is a type of detonator used to initiate the detonation reaction in explosive materials, similar to a blasting cap because it is fired using an electric current. EBWs use a different physical mechanism than blasting caps, using more electricity delivered much more rapidly. They explode with more precise timing after the electric current is applied by the process of exploding wire. The precise timing of exploding wire detonators compared with other types of detonators has led to their common use in nuclear weapons.
A triggering sequence, also called an explosive train or a firing train, is a sequence of events that culminates in the detonation of explosives. For safety reasons, most widely used high explosives are difficult to detonate. A primary explosive of higher sensitivity is used to trigger a uniform and predictable detonation of the main body of the explosive. Although the primary explosive itself is generally a more sensitive and expensive compound, it is only used in small quantities and in relatively safely packaged forms. By design there are low explosives and high explosives made such that the low explosives are highly sensitive and high explosives are comparatively insensitive. This not only affords inherent safety to the usage of explosives during handling and transport, but also necessitates an explosive triggering sequence or explosive train. The explosive triggering sequence or the explosive train essentially consists of an 'initiator', an 'intermediary' and the 'high explosive'.
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The British No. 69 was a hand grenade developed and used during the Second World War. It was adopted into service due to the need for a grenade with smaller destructive radius than the No. 36M "Mills bomb". This allowed the thrower to use a grenade even when there was little in the way of defensive cover. In contrast, the much greater destructive radius of the Mills bomb than its throwing range forced users to choose their throwing point carefully, in order to ensure that they would not be wounded by the shrapnel explosion of their own grenade.
Type 72 Non-Metallic is a Chinese circular, plastic bodied landmine which is designed to damage or destroy a vehicle by blast effect.
An anti-personnel mine or anti-personnel landmine (APL) is a form of mine designed for use against humans, as opposed to an anti-tank mine, which target vehicles. APLs are classified into: blast mines and fragmentation mines; the latter may or may not be a bounding mine.
The PMN series of blast anti-personnel mines were designed and manufactured in the Soviet Union. They are one of the most widely used and commonly found devices during demining operations. They are sometimes nicknamed "black widow" because of their dark casings.
The PMA-2 is a Yugoslavian blast antipersonnel mine. Sometimes referred to as the 'Pašteta', due to its superficial resemblance to a meat-pâté tin. The mine is constructed from dark green plastic, with a distinctive plunger which has six petals radiating from it.
In military munitions, a fuze is the part of the device that initiates its function. In some applications, such as torpedoes, a fuze may be identified by function as the exploder. The relative complexity of even the earliest fuze designs can be seen in cutaway diagrams.
An artillery fuze or fuse is the type of munition fuze used with artillery munitions, typically projectiles fired by guns, howitzers and mortars. A fuze is a device that initiates an explosive function in a munition, most commonly causing it to detonate or release its contents, when its activation conditions are met. This action typically occurs a preset time after firing, or on physical contact with or detected proximity to the ground, a structure or other target. Fuze, a variant of fuse, is the official NATO spelling.
A shock tube detonator is a non-electric explosive fuze or initiator in the form of small-diameter hollow plastic tubing used to transport an initiating signal to an explosive by means of a shock wave traveling the length of the tube. Shock tube is used to convey a detonation signal to a detonator. Shock tube is a hollow extruded tube containing a thin layer of energetic material upon its inner diameter. Once it is initiated, the shock tube transfers a signal to a detonating output charge.
The 37×145mmR was a series of rimmed-case, fixed-ammunition cannon shells for use in the 37mm Browning M4 autocannon.
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