Path: spln!rex!extra.newsguy.com!lotsanews.com!news.maxwell.syr.edu!news-out.visi.com!hermes.visi.com!gemini.tycho.net.POSTED!not-for-mail From: gherbert@gw.retro.com (George William Herbert) Newsgroups: sci.military.moderated Subject: Re: Unexploded ordnance Date: 24 Jan 2002 17:31:30 -0800 Organization: Retro Aerospace Approved: sci-military-moderated@retro.com Message-ID: <a2qchi$ic6$1@gw.retro.com> References: <OGG%7.12335$l93.2741551@newsb.telia.net> <a2p6cu$139dc9$1@ID-120108.news.dfncis.de> <3C5074C8.DFA1A31A@earthling.net> <a2q735$12vdmk$1@ID-7529.news.dfncis.de> Lines: 54 NNTP-Posting-Host: 52356c55.newsreader.tycho.net X-Trace: 1011921284 gemini.tycho.net 79553 205.179.181.194 X-Complaints-To: abuse@tycho.net Xref: spln sci.military.moderated:42150 Karl M. Syring <syring@email.com> wrote: >"Carey Sublette" <careysub@earthling.net> schrieb >> Don't use a primary explosive. >> An electrical detonator doesn't need to use a hot wire/primary explosive >> detonator. It can use a slapper detonator to initiate a booster or main >> charge explosive directly - PETN, which is safely used in primacord >> among other applications, is very easy to initiate this way for example. >> I know slapper detonators for bomblets have already been developed and >> tested, though I don't know if they are in service. > >Could you explain to us, how a slapper detonator works? Google reveals 1998 >patent (http://www.llnl.gov/str/Pat698.html), but I am not clear about the >exact mode of action. There are a whole family of types of detonators using variants on the same idea: rather than heat something up to detonate a sensitive explosive, you pump electrical energy into the system in sufficient quantity to cause a mechanical shockwave and thus detonate relatively insensitive explosives. The first variants were "exploding bridgewire" detonators, first used in the US nuclear weapons program as far as I can tell. These have a thin bridge wire between two posts surrounded by secondary HE such as PETN. Enough current is passed through the bridgewire in short enough time to vaporize it and cause a mechanical shockwave in the surrounding PETN. EBW and variants are relatively safe from heat (the HE doesn't have to be sensitive to / initiate by heating), stray electrical currents (anything other than sufficient voltage/current fast enough may melt the wire, but won't cause the detonating shockwave to form), and physical shock and such. Other early variants include "exploding foil initiators", where a similar arrangement is manufactured using conductive foils on a substrate of some sort, and thin-necked pinches in the foil conduction layer shapes. EFI are somewhat easier to manufacture and more reliable (the foil is less vulnerable to damage than a EBW wire is). There are also systems which use an intermediate mechanical transfer device on top of a foil or bridge wire, such as a plastic pellet which is accellerated by the exploding bridge and then impacts an area of explosive. One commercial manufacturer is RISI, with their website at: http://www.risi-usa.com/0products/index.html They make and provide info on classic EBW and EFI initiatiors. -george william herbert gherbert@retro.com