| A bridgewire, bridge wire, or hot bridge wire (HBW) is | | | | homogeneous heating of the entire bridgewire. This |
| a relatively thin resistance wire used to set off a | | | | may improve the bridgewire performance in some |
| pyrotechnic composition serving as pyrotechnic | | | | applications. |
| initiator. By passing of electric current it is heated to | | | | Bridgewires are used in diverse applications; to trigger |
| a high temperature that starts the exothermic | | | | detonators, electric matches, squibs, electric blasting |
| chemical reaction of the attached composition. After | | | | caps, pyrotechnic fasteners, and more. Bridgewires |
| successful firing, the bridgewire melts, resulting in an | | | | dipped in a suitable pyrotechnic composition |
| open circuit. | | | | (pyrogen) are known as electric matches. Pyrogens |
| Usually a thin nichrome wire is used. Some applications | | | | with content of magnesium allow reaching very high |
| also use platinum-silver alloy; other bridgewire | | | | combustion temperatures. |
| materials in use are platinum, gold, silver, tungsten, | | | | Devices using bridgewires, whether for initiating an |
| etc. Care has to be taken when selecting the material | | | | explosion ("electroexplosive") or for nonexplosive |
| as it is in direct contact with the pyrotechnic | | | | purposes, are called bridge wire actuated devices |
| composition and should not undergo corrosion in such | | | | (BWAD). |
| conditions. Another material, able to actively release | | | | Bridgewires, especially connected to longer cables, |
| chemical energy, is Pyrofuze, aluminium wire clad with | | | | may be susceptible to initiation by currents induced |
| palladium; when being heated it undergoes strongly | | | | by external electromagnetic fields. |
| exothermic reaction as the molten metals form an | | | | By passing an extremely high amount of electric |
| alloy. A variant with the same function consists of | | | | current through the bridgewire, it gets rapidly |
| laminated thin alternate layers of aluminium and nickel. | | | | vaporized, causing a small explosion. This is exploited |
| Carbon bridge is a thin spot of colloidal graphite used | | | | in exploding-bridgewire detonators (EBWs), used for |
| as the bridgewire. Some variants use a conductive | | | | very safe and highly precise initiation of explosives, |
| pyrotechnic composition as the resistive material. In | | | | e.g. in nuclear weapons. |
| amateur rocketry, grossly overloaded low wattage | | | | External links |
| metal film resistors and 0805 Surface-mount | | | | Bridgewire heating |
| technology resistors are also used. | | | | This explosives-related article is a stub. You can help |
| A shallow notch cut into the center of the bridgewire | | | | Wikipedia by expanding it. |
| promotes gross localized overheating instead of | | | | |