Insensitive High Explosive Initiators

The initiation of propagating, diverging detonation is usually accomplished by using small conventional initiators however, as the explosives to be initiated became more shock insensitive, the initiators must have larger diameters ( 2.54 cm) to be effective. 

Travis has used the image intensifier camera to examine the nature of the diverging detonation waves formed in PBX-9404, PBX-9502 (X0290), and X0219 by hemispherical initiators. The geometries of the initiators were (1) a 0.635 cm radius hemisphere of PBX-9407 at 1.61 g/cc surrounded by a 0.635 cm radius hemisphere of PBX-9404, (2) a 0.635 cm radius hemisphere of 1.7 g/cc TATB surrounded by a 1.905 cm thick hemisphere of 1.8 gm/cc TATB, or (3) a 1.6 cm radius hemisphere of X0351 (15/5/80 HMX/Kel-F/TATB) at 1.89 g/cc. 

Animations of a PBX-9404 hemispherical initiator in PBX-9502 generated using the NOBEL code are on the CD-ROM in the /MOVIE/DET.MVE directory. 

The calculations were done in cylindrical geometry with Lucite conflnement rather than the air confinement present in the experimental study. The Lucite conflnement prevents the mesh distortion that can be fatal to Lagrangian calculations. 

The central 0.635 cm region of the detonator was initially exploded, which initiated the remaining explosive in the detonator using a C-J volume burn. For any given mesh size and time step, the viscosity must be adjusted to give a peak pressure at the detonation front near the effective C-J pressure. 

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Charles L. Mader Numerical Modeling of Insensitive High-Explosive Initiators , Los Alamos Scientific Laboratory report LA-8437-MS (1980). 

The modeling of insensitive high explosive initiators using the 2DL, 2DE and 3DE codes is described in Chapter 5, section 5.8. While the build-up to detonation process was described using Forest Fire, it was not possible to also investigate the build-up of detonation until the development of the NOBEL code described in this chapter. 

C. D. Hutchinson and co-workers, "Initiation and Detonation Properties of the Insensitive High Explosive TATB/KEL-F800 95/5," Vol. 1, in... 

H. R., and Jones, A.G. (1989) Initiation and detonation properties of the insensitive high explosive TATB/Kel-F800 95/5. Proc. 9th Symp. (Inti.) on Detonation, Portland, Oregon, USA, p. 123. 

Since the initiators for insensitive high explosives must be very large to initiate propagating detonation, other methods have been studied to achieve the required high pressures of adequate duration. High pressures are achieved if two or more shock waves interact to form regular or Mach shock interactions. 

The use of multiple shock wave interactions to initiate propagating detonation has been studied experimentally by Goforth . He observed that while double shock wave interactions were sometimes inadequate to initiate propagating detonation, triple shock wave interactions could be generated that initiated propagating detonation in insensitive high explosives. 

Because this improvised explosive is extremely insensitive, a booster is required to initiate it. A half pound charge of any high explosive in the bottom of the hole will be sufficient to insure detonation. 

Civil explosives are also known as commercial or blasting explosives and are typically used for mining, quarrying, construction and tunnel building. They are chemical compositions, which detonate when initiated by high explosive primers or boosters or directly by detonators. They are relatively insensitive to shock, friction or impact... 

The discovery of the phenomenon of initiation by Alfred Nobel and the invention of the blasting cap14 stand at the beginning of the development of modern explosives, perhaps the most important discovery and invention in the history of the art. The phenomenon has supplied a basis for the definition of high explosives, that is to say, of those explosives, whether sensitive or insensitive, which are incapable, without the invention, of being used safely and controllably or perhaps even of being used at all. 

Secondary High Explosives. A high expl which is relatively insensitive to heat and shock and is usually initiated by a primary high explosive,... 

Properties White crystals. Sp. gr. 1.725. M. P. 155-166°. Decomposes at 210°. Very hygroscopic. Explosives containing ammonium nitrate may be protected from moisture by suitable coating, such as oily nitro compounds, or by selection of waterproof material for cartridges (paraffin). It is a high explosive, very insensitive to impact and difficult to detonate, requiring a combination of an initiator and a high explosive (reinforced detonators). 

Research and development is continuing in the chemistry of explosives to produce compounds that are insensitive to accidental initiation but still highly efficient as explosives. NTO (7), ADN (8), and TNAZ (9) are good examples of explosive compounds under development and testing. 

Part of an explosive train which initiates the - detonation of high explosives, especially of insensitive ones. It may itself be triggert by a seperate -> primer of primary explosives or an integrated primer. Detonators are classified by the method of initiation percussion, stab, electrical impulse, or flash. Laser initiation is also used. Depending on the application detornators can include a delay mechanism. Explosive charge placed in certain equipment and set to destroy the equipment under certain conditions (- Initiator). 

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