Editing Detonator (section)

== Blasting caps ==
[[File:Cutaway diagram of various types of blasting caps and detonators.svg|thumb|Cutaway diagram of various types of blasting caps and detonators]]

The oldest and simplest type of cap, fuse caps are a metal cylinder, closed at one end.  From the open end inwards, there is first an empty space into which a pyrotechnic [[fuse (explosive)|fuse]] is inserted and crimped, then a pyrotechnic ignition mix, a [[primary explosive]], and then the main detonating explosive charge. The primary hazard of pyrotechnic blasting caps is that for proper usage, the fuse must be inserted and then crimped into place by crushing the base of the cap around the fuse.  If the tool used to crimp the cap is used too close to the explosives, the primary explosive compound can detonate during crimping.  A common hazardous practice is crimping caps with one's teeth; an accidental detonation can cause serious injury to the mouth. Fuse type blasting caps are still in active use today.  They are the safest type to use around certain types of electromagnetic interference, and they have a built in time delay as the fuse burns down.

Solid pack electric blasting caps use a thin [[bridgewire]] in direct contact (hence solid pack) with a primary explosive, which is heated by electric current and causes the detonation of the primary explosive.  That primary explosive then detonates a larger charge of secondary explosive. Some solid pack fuses incorporate a small pyrotechnic delay element, up to a few hundred milliseconds, before the cap fires.

Match type blasting caps use an [[electric match]] (insulating sheet with electrodes on both sides, a thin bridgewire soldered across the sides, all dipped in ignition and output mixes) to initiate the primary explosive, rather than direct contact between the bridgewire and the primary explosive.  The match can be manufactured separately from the rest of the cap and only assembled at the end of the process. Match type caps are now the most common type found worldwide.

The [[exploding-bridgewire detonator]] was invented in the 1940s as part of the [[Manhattan Project]] to develop nuclear weapons.<ref>{{Cite web |last=Laboratory |first=Los Alamos National |title=Detonator Production {{!}} Organizations |url=https://organizations.lanl.gov/dp-division/past/ |access-date=2024-08-21 |website=Los Alamos National Laboratory |language=en}}</ref>  The design goal was to produce a detonator which functioned very rapidly and predictably).  Both Match and Solid Pack type electric caps take a few milliseconds to fire, as the bridgewire heats up and heats the explosive to the point of detonation.  Exploding bridgewire or '''EBW''' detonators use a higher voltage electric charge and a very thin bridgewire, .04 inch long, .0016 diameter, (1&nbsp;mm long, 0.04&nbsp;mm diameter).  Instead of heating up the explosive, the EBW detonator wire is heated so quickly by the high firing current that the wire actually vaporizes and explodes due to electric resistance heating.<ref>{{Cite report |url=https://www.osti.gov/biblio/1458273 |title=Physical and Electrical Measurements of Different Materials used in EBW Detonators. |last1=Valancius |first1=Cole Joseph |last2=Bainbridge |first2=Joe |date=2017-02-01 |publisher=Sandia National Lab. (SNL-NM), Albuquerque, NM (United States) |issue=SAND2017–1769C |language=English |last3=Richardson |first3=Duane Ross |last4=Love |first4=Cody Wade|osti=1458273 }}</ref>  That electrically-driven explosion causes the low-density initiating explosive (usually [[PETN]]) to detonate, which in turn detonates a higher density secondary explosive (typically RDX or HMX) in many EBW designs.<ref>{{Cite web |title=EBW Detonators |url=https://www.teledynedefenseelectronics.com/energetics/products/Pages/EBW%20Detonators.aspx |access-date=2024-08-21 |website=www.teledynedefenseelectronics.com}}</ref> In addition to firing very quickly when properly initiated, EBW detonators are much safer than blasting caps from stray static electricity and other electric current.  Enough current will melt the bridgewire, but it cannot detonate the initiator explosive without the full high-voltage high-current charge passing through the bridgewire.  EBW detonators are used in many civilian applications where radio signals, static electricity, or other electrical hazards might cause accidents with conventional electric detonators.


Exploding foil initiators (EFI), also known as [[Slapper detonator]]s are an improvement on EBW detonators.<ref name=":0">{{Cite report |url=https://ntrl.ntis.gov/NTRL/dashboard/searchResults/titleDetail/UCRL77639.xhtml |title=New Kind of Detonator: The Slapper. |last=Stroud |first=J. R. |date=1976 |publisher=California Univ., Livermore. Lawrence Livermore Lab.; Energy Research and Development Administration. |issue=UCRL77639}}</ref><ref>{{Cite journal |last1=Yang |first1=Zhi |last2=Zhu |first2=Peng |last3=Chu |first3=Qing-yun |last4=Zhang |first4=Qiu |last5=Wang |first5=Ke |last6=Jian |first6=Hao-tian |last7=Shen |first7=Rui-qi |date=2022-08-01 |title=A micro-chip exploding foil initiator based on printed circuit board technology |journal=Defence Technology |volume=18 |issue=8 |pages=1435–1444 |doi=10.1016/j.dt.2021.06.008 |issn=2214-9147|doi-access=free }}</ref>  Slappers, instead of directly using the exploding foil to detonate the initiator explosive, use the electrical vaporization of the foil to drive a small circle of insulating material such as [[PET film (biaxially oriented)|PET film]] or [[kapton]] down a circular hole in an additional disc of insulating material.  At the far end of that hole is a pellet of high-density secondary explosive.<ref name=":1">{{Cite journal |last1=Rae |first1=P. J. |last2=Dickson |first2=P. M. |date=July 2019 |title=A review of the mechanism by which exploding bridge-wire detonators function |journal= Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences|volume=475 |issue=2227 |pages=20190120 |doi=10.1098/rspa.2019.0120 |issn=1364-5021 |pmc=6694310 |pmid=31423094|bibcode=2019RSPSA.47590120R }}</ref> Slapper detonators omit the low-density initiating explosive used in EBW designs and  they require much greater energy density than EBW detonators to function, making them inherently safer.<ref name=":0" />

Laser initiation of explosives, propellants or pyrotechnics has been attempted in three different ways, (1) direct interaction with the HE or Direct Optical Initiation (DOI); (2) rapid heating of a thin film in contact with a HE; and (3) ablating a thin metal foil to produce a high velocity flyer plate that impacts the HE (laser flyer).<ref name=":1" /><ref>{{Cite web |last1=Yong |first1=Leo de |last2=Nguyen |first2=Tam |last3=Waschl |first3=John |date=May 1995 |title=Laser Ignition of Explosives, Pyrotechnics and Propellants: A Review |url=https://apps.dtic.mil/sti/pdfs/ADA299465.pdf |website=Defense Technical Information Center |publisher=Defense Science and Technology Organisation (DSTO)}}</ref>