Firing System
The EBW and the slapper detonator are the safest known 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 discharging a low-inductance, high-capacitance, high-voltage capacitor (e.g. oil-filled, Mylar-foil, or ceramic) through a suitable switch (spark gap, thyratron, krytron, etc.) into the bridge wire. The ballpark figures are 5 kilovolt and 1 microfarad rating for the capacitor, and the peak current required ranges between 500 and 1000 amperes. The wire used in the bridge tends to be highly pure gold or platinum, 0.02–-0.05 mm in diameter, and 1 mm long. The high voltage may be generated using a Marx generator. Low-impedance capacitors and low-impedance coaxial cables are required to achieve the necessary current rise rate.
A possible alternative for bulky (*see note below) capacitors is the flux compression generator. When fired, it creates a strong electromagnetic pulse, which is inductively coupled into one or more secondary coils connected to the bridge wires or slapper foils.
In a fission bomb the same or similar circuit is used for powering the neutron trigger, the additional booster source of fission neutrons.
The energy in such a capacitor would be 1/2 C V2, which for the above mentioned cap is 12.5J. The capacitor would be small even if a low energy density one was used (soda can size).
By comparison, a defibrillator delivers ~200J from 2Kv and perhaps 20 uF. The flash-strobe in a disposable camera is typically 3J from a 300V capacitor of 100uF.
Read more about this topic: Exploding-bridgewire Detonator
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