Detonator
A detonator is an initiating device used to explode bombs, explosive charges, and other types of explosive material and blasting devices. There are three categories of detonators according to their delay: electric or non-electric instantaneous (DEI) detonators, short period detonators (DPC) and long period detonators (DPL). DPC detonators measure delay time in milliseconds while DPL detonators measure it in seconds. Depending on their mechanism of action: chemical, mechanical or electrical, the latter two being the most frequent types used today. In military explosive ordnance devices (MEMs), such as hand grenades or naval mines, the detonators are usually mechanical. On the contrary, in the commercial use of explosives, the use of non-electric detonators (Nonel) is more common, which have displaced electric ones due to their greater safety.
Types
They can be mainly differentiated into two types: electric and non-electric, although today some companies are already marketing electronic detonators, which are much more reliable than electric ones and more precise than non-electric ones.
The fundamental difference between electric and non-electric is that the electric ones are activated by an electrical stimulus and the non-electric ones need another type of stimulus such as heat or a shock wave activated through a transmission tube, for example..
Composition
In commercial detonators, you can find various normal detonators that have sensitive fuses (mostly heat, shock or touch) added to the top. These fuses mostly have a material called 'ASA', composed of: lead azide, lead styphnate and aluminum. Once compressed, it is placed on top of the explosive charge, TNT or tetryl in military detonators and PETN in commercial detonators. Other materials such as DDNP (diazodinitrophenol) are mainly used to reduce the amount of lead emitted into the atmosphere from mining and quarrying operations. The old detonators used mercury fulminate, sometimes mixed with potassium chlorate to get more power, although more and more are falling into disuse due to the great pollution they generated. Detonators vary greatly in both shape and size, making it impossible to establish a detonator number for each type that exists today.
Triggers in other fields
In thermonuclear weapons, the trigger is a fission bomb that causes nuclear fusion reactions.
In situations where nanosecond precision is needed, especially in nuclear warheads, bridgewire detonators are used. These types of detonators do not carry any explosive charge, but produce the detonation by means of an electric discharge and passing it through a very fine wire.
New developments
A new development of detonators are flat detonators. These detonators use very thin plates electrically charged by a wire or silver foil to cause the first discharge. This is the method used in weapon systems today. A variant of this concept is used in mining excavations, where silver foil plates are actuated by a laser via a fiber optic cable.