​​​​RP EBW Detonator​. P/N ​. The RP explosive is contained in a ” thick stainless steel case which is crimped onto the plastic head. OPEN ACCESS. A view on the functioning mechanism of EBW detonators -part 1: electrical characterisation. To cite this article: E A Lee et al J. Phys.: Conf. Exploding Bridgewire (EBW) Detonators are in widespread use and have proven reliability and performance characteristics. Since their invention there have.

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The exploding-bridgewire detonator EBWalso eba as exploding wire detonator is a type of detonator used to initiate the detonation reaction in explosive materialssimilar to a blasting cap because it is fired using an electric current.

EBWs use a different physical mechanism than blasting caps, using more electricity delivered much more rapidly, and explode in a much more precise timing after the electric current is applied, by the process of exploding wire method. This has led to their common use in nuclear degonator.

The slapper detonator is a more recent development along similar lines. The Fat Man Model EBW detonators used an unusual, high reliability detonator system with detonatorr EBW detonaor attached to a single booster charge, ebq then fired each of the 32 explosive lens units. EBWs were developed as a means of detonating multiple explosive charges simultaneously, mainly for use in plutonium-based nuclear weapons in which detoator plutonium core called a pit is compressed very rapidly.

This is achieved via conventional explosives placed uniformly around the pit. The implosion must be highly symmetrical or the plutonium would simply be ejected at the low-pressure points. Consequently, the detonators must have very precise timing. An EBW has two main parts: When the wire is vetonator across this voltage, the resulting high current melts and then vaporizes the wire in a few microseconds. The resulting shock and heat initiate the high explosive. Closeup of a detonator set.

The EBW is the Y-shaped device with two wires coming in at angles along the surface. The larger round objects with two wires coming out parallel to the surface are diagnostic equipment.

Closeup with EBW highlighted. Booster charge circled in green. Two EBW arms circled in light green. Detonator wires highlighted in yellow. This accounts for the heavy cables seen in photos of the Trinity ” Gadget “; high voltage cable requires good insulation and they had to deliver a large current with little voltage drop, lest the EBW not achieve the phase transition quickly enough.


The precise timing of EBWs is achieved by the detonator using direct physical effects of the vaporized bridgewire to initiate detonation in the detonator’s booster charge.

Given a sufficiently high detnoator well known amount of electric current and voltage, the timing of the bridgewire vaporization is both extremely short a few microseconds and extremely precise and predictable standard deviation of time to detonate as low as a few tens of nanoseconds.

RP-1 EBW Detonator

Conventional blasting caps use electricity to heat a bridge wire rather than vaporize it, and that heating then causes the primary explosive to detonate. Imprecise contact between the bridgewire and the primary explosive changes how quickly the explosive is heated up, and minor electrical variations in the wire or leads will change how quickly it heats up as well.

The heating process typically takes milliseconds to tens of milliseconds to complete and initiate detonation in the primary explosive. This is roughly 1, to 10, times longer and less precise than the EBW electrical vaporization.

Since explosives detonate at typically 7—8 detnator per second, or 7—8 meters per millisecond, a 1 millisecond delay in detonation from one side of a nuclear weapon to the other would be longer than the time the detonation would take to cross the weapon. The time precision and consistency of EBWs 0.

This is sufficiently precise for very low tolerance applications such as nuclear weapon explosive lenses. In the US, due to their common use in nuclear weapons, these devices are subject to the nuclear control authorities in every state, detonattor to the Guidelines for the Export of Nuclear Material, Equipment and Technology.

EBWs have found uses outside nuclear weapons, such as the Titan IV[5] safety conscious applications where stray electrical currents might detonate normal blasting caps, and applications requiring very precise timing for multiple point commercial blasting in mines or quarries. Primary explosives such as lead azide are deonator sensitive to static electricity, radio frequency, shock, etc.

The most common commercial wire size is 0.

From the available explosives, only PETN at low densities can be initiated by sufficiently low shock to make its use practical in commercial systems as a part of the EBW initiator. Detonators without such booster are called initial pressing detonators IP detonators.

During initiation, the wire heats with the passing current until melting point is reached. The heating rate is high enough that the liquid metal has no time to flow away, and heats further detonaor it vaporizes. During this phase the electrical resistance of the bridgewire assembly rises.


Then an electric arc forms in the metal vapor, leading to drop of electrical resistance and sharp growth of wbw current, quick further heating of the ionized metal vapor, and formation of a shock wave. To achieve the melting and subsequent vaporizing of the wire in time sufficiently short to create a shock wave, a current rise rate of at least amperes per microsecond is required.

If detonatof current rise rate is lower, the bridge may burn, perhaps causing deflagration of the PETN pellet, but it will not cause detonation.

Their use is limited by the thermal stability range of PETN. The EBW and the slapper detonator are the safest detonxtor types of detonators, as only a very high-current fast-rise pulse can successfully trigger them. However, they require a bulky power source for the current surges required.

The extremely short rise times are usually achieved by cetonator a low- inductancehigh-capacitance, high-voltage capacitor e. A very rough approximation for the capacitor is a rating enw 5 kilovolts and 1 microfarad, and the peak current ranges between and detonqtor. Low- impedance capacitors and low-impedance coaxial cables are required to achieve the necessary current rise rate.

The flux compression generator is one alternative to capacitors. When fired, it creates a strong electromagnetic pulsewhich is inductively coupled into one or more secondary coils connected to the bridge wires or slapper foils. A low energy density capacitor equivalent to a compression generator would be roughly the size of a soda can.

In a fission bomb, the same or similar circuit is used for powering the neutron triggerthe initial source of fission neutrons.

From Wikipedia, the free encyclopedia. Modern exploding-bridgewire detonators arranged in a tray.

A view on the functioning mechanism of EBW detonators -part 1: electrical characterisation

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