Bulletin of the American Physical Society
20th Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 62, Number 9
Sunday–Friday, July 9–14, 2017; St. Louis, Missouri
Session Z3: Detonation and Shock Induced Chemistry: Detonators and Shock Initiation |
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Chair: Eric Anderson, Los Alamos National Laboratory Room: Grand Ballroom FG |
Friday, July 14, 2017 11:15AM - 11:30AM |
Z3.00001: Shock initiation of the TATB-based explosive PBX 9502 heated to 130 degrees C R. L. Gustavsen, B. D. Bartram, L. L. Gibson, A. H. Pacheco, J. D. Jones, A. B. Goodbody We present gas-gun driven plate-impact shock initiation experiments on the explosive PBX 9502 (95 weight {\%} triaminotrinitrobenzene, 5 weight {\%} Kel-F 800 binder) heated to 130 $+$/- 2 degrees C. PBX 9502 samples were heated using resistive elements, temperatures were monitored using embedded and surface mounted type-E thermocouples, and the shock to detonation transition was measured using embedded electromagnetic particle velocity gauges. Results indicate that shock sensitivity increases regularly as the temperature increases. For a fixed initial pressure, the time and distance to onset of detonation are shorter for the heated explosive than for the explosive initially at 23 degrees C. For PBX 9502 heated to 130 degrees C, the ``Pop-plot'' or distance to detonation, $x_{D}$, vs. impact pressure, $P$, is log$_{\mathrm{10}}(x_{D}) \quad =$ 2.82 - 2.19 log$_{\mathrm{10}}(P)$. [Preview Abstract] |
Friday, July 14, 2017 11:30AM - 11:45AM |
Z3.00002: Experimental Observations of Detonator Function Laura Smilowitz, Bryan Henson, Dennis Remelius, David Oschwald, Natalya Suvorova, Keith Thomas Exploding bridge wire, EBW, detonators are one of a few types of commercially available detonators. Their use is widespread, and they have been successfully used for over a half century. However, despite their robust function, the mechanism of function remains controversial. References definitively attributing EBW function to either shock or deflagration can both be found. In this work, we have applied a suite of diagnostics to observing the function of commercial EBW detonators. These diagnostics include traditional current, voltage, and light output as well as the addition of table-top flash radiography and the application of ultra-high speed cameras. We observe an initial thermal response spatially coincident and preceding what will be the apparent center of initiation of detonation. This initial response is observed in the IR, but not in the visible. This talk will present the experimental observations from our diagnostics and attempt to define what we know from direct observation as well as present a hypothesis for mechanism consistent with both our observations, and those previously reported by other groups. [Preview Abstract] |
Friday, July 14, 2017 11:45AM - 12:00PM |
Z3.00003: Thermal response of PETN in the function of Exploding Bridgewire Detonators Bryan Henson, Laura Smilowitz We have recently produced a family of chemical decomposition models applicable to the thermal response of secondary explosives. In this talk we present applications of this model to the response of porous PETN in the function of exploding bridgewire detonators. In experiments fielding a suite of x-ray radiographic, visible imaging and internal sensors we observe an initial thermal response spatially coincident with and preceding what will be the apparent center of initiation of detonation in these devices.~ This initial response is observed in the infrared, but not in the visible. We show that an initial thermal response of the PETN powder to the vaporizing bridgewire is consistent with the subsequent very prompt evolution to initiation and detonation. [Preview Abstract] |
Friday, July 14, 2017 12:00PM - 12:15PM |
Z3.00004: Assessing the Effect of the Role of Detonation Wave Curvature on the Firing Times of High Voltage Detonators Rod Drake In detonators the lost time is the difference between the measured and calculated time for the reactive wave to transit the explosive charge. The calculated time is derived from the charge thickness and the steady state detonation velocity. For both EBW and EFI detonators the lost time is significant and, for detonators of comparable dimensions, greater in EBW detonators. Typically, the lost time is attributed to a finite growth to detonation time. The bridgewires and foil flyers of EBW and EFI detonators respectively establish reaction fronts over very small areas in the explosive. Even with a significant run to detonation distance, the detonation front may be expected to be highly curved and, thus, have a detonation velocity below the steady state velocity. Consequently, the time and distance required for a steady state detonation velocity to be established may also contribute to the lost time in EBW and EFI detonators. To assess the relevance of wave curvature on lost time a simple analytical model has been developed which takes into account growth to detonation and detonation wave curvature effects. The model showed that detonation wave curvature could be responsible for at least some of the lost time of EBW detonators. British Crown Owned Copyright 2017/AWE [Preview Abstract] |
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