Editing Explosive booster

{{Short description|Sensitive explosive charge}}
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{{unreferenced|date=August 2011}}
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 [[trinitrotoluene|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 [[C-4 (explosive)|C4]] [[plastic explosive]], not all explosives can be detonated simply by inserting a detonator and firing it.

An initiator such as a [[Shock tube detonator|shock tube]], cannon [[Fuse (explosives)|fuse]], or even a conventional [[detonator]] does not deliver sufficient shock to [[detonate]] charges comprising [[Trinitrotoluene|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At first, [[picric acid]] was used as a booster to detonate TNT, though it was superseded due to the inherent danger of [[picrate]] formation.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 However, since then, tetryl has largely been replaced by other compositions, e.g. a small cylinder or pellet of [[phlegmatized]] [[RDX]] (e.g. CH-6 or Composition A-5) or [[PETN]] (slightly larger than the actual [[detonator]]) into which the detonator itself is inserted.

Note: [[booby trap]]s and [[improvised explosive device]]s frequently use [[plastic explosive]] as the booster charge, for example, some [[C4 explosive|C4]] or [[Semtex]] stuffed into the empty [[fuze]] pocket of a 120mm [[mortar shell]]. This is because any standard detonator will initiate plastic explosive as is.

When encountered in connection with artillery shells or air dropped bombs, a booster charge is sometimes referred to as the "gaine", from {{langx|fr|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 [[Explosive_material#Primary_explosive|primary explosives]]) much more sensitive to shock, heat, and friction than an explosive booster. Therefore, minimising the amount of primary explosive 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==
<gallery widths=270px heights=250px>
Image:M1-M4 mine cutaway.JPG|Cross-sectional view of an [[M1_mine|M4 mine]] showing the [[detonator]] and adjacent booster charge surrounded by the main explosive charge of [[trinitrotoluene|TNT]]
Image:BLU-43B_internal.jpg|Cross-sectional view of a [[BLU-43 Dragontooth]] [[cluster munition]] showing detonator and adjacent booster charge
Image:M14 mine cutaway - internal view.png|Cut-away view of an [[M14 mine|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
File:PG-2 rocket.png|Cut-away view of an [[RPG-2]] rocket grenade showing booster charge
File:M2A4_mine_M6A1_fuze.jpg|Cut-away view of a [[M2 mine]] showing booster charge above detonator
File:US_Navy_101116-N-8546L-728_A_Uruguayan_army_explosive_ordnance_disposal_officer,.jpg|A group of 105&nbsp;mm [[artillery shell]]s 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.
</gallery>

[[Category:Explosives]]