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  • American Institute of Physics (AIP)  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    The initiation of fine grain pentaerythritol tetranitrate by laser-driven flyer plates (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 65-69 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Charges of pentaerythritol tetranitrate (PETN) were impacted by laser-driven flyer plates launched from substrate backed aluminum films. The flyers were produced by single pulses from a Q-switched Nd:YAG laser. The aluminum flyers were between 3 and 5 μm thick, had diameters of 1 mm, and achieved velocities up to 8 km s−1. The stresses were intense but of only nanosecond duration. This falls into an interesting regime since the shock thickness of a few microns is of the order of typical hot-spot sizes and less than the grain size of conventional explosive powders. Ultrafine PETN (∼1 μm grain size) was readily initiated, whereas conventional, 135 sieve PETN with a grain size of 106 μm was not, although limited reaction was observed in some cases. Environmental scanning electron microscopy was carried out to help elucidate the differences in behavior. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.373625
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  • 2
    Electronic Resource
    Electronic Resource
    Anomalous detonation velocities following type II deflagration-to-detonation transitions in pentaerythritol tetranitrate (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 4995-5001 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The detonation velocity following type II deflagration-to-detonation transitions (DDT) has been observed to be markedly different to that which would be expected were the charges directly initiated. In charges of pentaerythritol tetranitrate (PETN) velocities as high as 5.6 mm μs−1 have been observed compared to 3.7 mm μs−1 which is both predicted and measured for the charge were it to be directly initiated. Experiments have also been carried out that attempt to measure the temperature within columns of PETN prior to a type II DDT event. Other experiments and hydrocode simulations have been carried out that attempt to isolate the possible causes of the anomalous detonation velocity and as a result determine what the critical factors that determine the velocity are. These studies have led to a greater understanding not only of the reasons behind the change in detonation velocity, but also of the stages that occur in the build up to type II DDT. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1462415
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  • 3
    Electronic Resource
    Electronic Resource
    A new mechanism for deflagration-to-detonation in porous granular explosives (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 1749-1753 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An investigation has been carried out into the differences between the deflagration-to-detonation (DDT) process as it occurs in low density [∼30% theoretical maximum density (TMD)] columns of conventional grain size (∼180 μm) pentaerythritol tetranitrate (PETN) and in ultrafine PETN with a grain size ∼1 μm. The principle technique for observing the process utilized charges confined within a steel housing fitted with a polycarbonate slit window. This allowed direct recording of the transition using high speed streak photography. The explosive was thermally ignited using a pyrotechnic mixture with low gaseous emission to minimize any prepressurization of the charge. In addition to the photographic records of the events, the outputs of photodiodes along the length of the column were monitored in order to determine the rate at which the reaction proceeds. The results obtained show that the DDT process in the larger grain PETN at low density was similar in structure to the DDT process at higher densities. In contrast a different mechanism leads to detonation in columns composed of the smaller grain size PETN when packed to densities less than 50% TMD. After ignition hot gases propagate along the column both compacting and igniting material as they pass. After the gases have reached the downstream end of the column, the column continues to burn and the pressure and temperature increase. Some time later initiation takes place at a point along the burning column, and detonation waves propagate in both directions from this point. The detonation waves propagate from the initiation point at speeds that would normally be associated with material compacted to around 60% TMD. The process appears to be in effect a deflagration-to-localized thermal explosion detonation transition. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.370957
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