Explosive train

Abstract: A transfer unit is sealingly connected to a pressure tight housing. The pressure tight housing includes a detonator and electronics circuits connected to the detonator, the pressure tight housing being adapted to be disposed in a well apparatus situated in a wellbore. The wellbore contains fluids at high temperature and pressure, and the pressure tight housing protects the detonator and electronics from the severe temperature and pressure of the wellbore fluids. The transfer unit receives, on one end, the detonator and, on the other end, a separate detonating cord which is adapted to be connected to another separate explosive device and includes a pressure proof housing and a matrix of secondary explosive disposed in a compressed condition within the pressure proof housing between the detonator and the detonating cord, the matrix of secondary explosive functioning like a transversely disposed bulkhead or barrier for protecting the detonator and associated electronics from the severe temperature and pressure of the wellbore fluids which exists adjacent the detonating cord. Although the secondary explosive bulkhead is compressed within the pressure proof housing, the detonating cord may penetrate the secondary explosive bulkhead in response to the high pressure of the external wellbore fluids. Therefore, in order to prevent this penetration, the pressure proof housing includes a neck down portion disposed peripherally around the secondary explosive bulkhead in order to further compress the secondary explosive and to prevent the detonating cord from penetrating the secondary explosive bulkhead in response to the high pressure of the wellbore fluids.

Abstract: Optical energy, provided from a remote user-operated source, is utilized to initially electrically charge a capacitor in a circuit that also contains an explosion initiating transducer in contact with a small explosive train contained in an attachable housing. Additional optical energy is subsequently supplied in a preferred embodiment to an optically responsive phototransistor acting in conjunction with a silicon controlled rectifer to release the stored electrical energy through the explosion initiating transducer to set off the explosive train. All energy transfers between the user and the explosive apparatus, either for charging it up or for setting it off, are conveyed optically and may be accomplished in a single optical fiber with coding to distinguish between specific optical energy transfers and between these and any extraneous signals.

Abstract: An explosive detonator consisting of an integrated circuit chip having a silicon substrate on which is formed an amorphous or polysilicon bridge, the bridge extending between two metal wire-bonding pads also on the substrate. The integrated circuit chip is disposed in close proximity to a primary charge such that when the bridge is energized by an electric current, it heats to the point where the charge is ignited. By back-etching the silicon substrate under the bridge, parasitic heat conduction is avoided. Further, by bonding a pyrex tube to the chip with the tube's bore surrounding the bridge, it is possible to pack the bore with an explosive train in fabricating the detonator assembly.

Abstract: In small caliber ammunition, an explosive train for igniting the main prolant charge within the cartridge, said explosive train comprising a shock-sensitive percussion primer and a shock-resistant booster charge. The booster charge is formed as a single annular pellet coaxially aligned with the primer. The primer generates a jet of flame through the central hole in the booster pellet, thereby igniting the pellet to a self-heated condition sufficient to ignite the main propellant charge.