Characterization of high explosives by observing growth to detonation

Mohler, Jonathan H.; Moodie, W.J.; Haws, L.D.; Hall, G.F.

doi:10.1016/0010-2180(78)90103-7

Cited by 4 publications

(8 citation statements)

References 2 publications

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“…In both cases, the optical observation was made at a sufficient distance from the ignition site that either a very strong but still building reaction shock or a full detonation arrived, but the resulting spatial time of arrival at the walls was complex. In the case of the purely axial time-of-arrival measurements presented in [33], similar times of arrival data were obtained to the new results presented in this paper.…”

Section: Explosive Powder Studiessupporting

confidence: 81%

“…For comparison, the PETN used in this study had a SA of 5800 cm 2 g −1 while the PETN used in the RP-80 (relevant to much of [27]) is lower at ≈ 3000 cm 2 g −1 . Comparing the RP-1 PETN with the data in [33] suggests a run distance to detonation of 3.5 mm is reasonable for the RP-1 PETN. Given the 4.98 mm long low-density pressing in the RP-80 and the lower SA, it is possible that the reaction has barely transitioned to a steady state by the time the shock reaches the high-density output pellet.…”

Section: Explosive Powder Studiesmentioning

confidence: 69%

“…The new data presented here and in [17] do not have sufficient resolution to fully prove or disprove this explanation, but do indicate that the transition to steady-state detonation occurs relatively far from the bridge where the curvature effects are less significant. However, the data in [33] do demonstrate that in some high SA PETN steady-state detonation can occur promptly and without a detonation curvature delay effect along the axis of the detonator (i.e., with imperceptibly low ETT).…”

Section: Explosive Powder Studiesmentioning

confidence: 81%

“…The functioning of special SE-1 detonators (a design almost identical to the RP-1) was investigated in [33] as a function of PETN particle size. The key diagnostic was timeof-arrival optical fibers placed either in the header (radially separated from the bridge), in the sleeve wall (both radially and axially separated from the bridge), or in plastic plugs placed on top of variable height PETN pressings (axially separated).…”

Section: Explosive Powder Studiesmentioning

confidence: 99%

“…The result of these processes is a complex slowing of the speed of propagation in areas of high curvature, such as those close to an exploding bridgewire. It is believed that this accounts for the difficult to interpret optical signals results in both [27,33]. In both cases, the optical observation was made at a sufficient distance from the ignition site that either a very strong but still building reaction shock or a full detonation arrived, but the resulting spatial time of arrival at the walls was complex.…”

Section: Explosive Powder Studiesmentioning

confidence: 99%

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The effects of electrically exploding gold bridgewires into inert and explosive powder beds

Rae

Rettinger

2021

Shock Waves

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The particle velocity created in beds of both low-density inert sugar and explosive PETN as a function of distance from an exploding bridgewire was measured using optical velocimetry and a silvered PMMA window. As expected, more violent bridge-bursts (from a greater-stored-energy capacitive discharge unit) resulted in greater particle velocities and a better supported compaction wave in sugar. In all cases, ramp waves, not shocks, were observed in the inert sugar. Large window velocities were observed for very powerful bursts (up to 270 m/s), but bursts required for stochastic detonator operation conditions resulted in sugar/PMMA window velocities of only 8–10 m/s 0.85 mm from the bridge location. In contrast, after a distance of only 0.65 mm, a building shock wave was observed in PETN under both threshold and reliable firing conditions. Subsequently a hot-spot-driven shock-to-detonation (SDT) process was observed prior to full detonation. The measured buildup process accounts for $$\approx $$ ≈ 66% of the so-called excess transit time (ETT) between the observed and theoretical total function time for the particular exploding-bridge-wire (EBW) detonator studied. The remainder must occur in the powerful output pellet region. In contrast to a common understanding, the ETT is found to be a weak function of the discharge energy. Thus, the operation of the detonator after a bridge-burst energy-to-powder reaction transition process is found to be hot-spot-driven SDT in both the low- and high-density pellets.

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Section: Explosive Powder Studiessupporting

confidence: 81%

Section: Explosive Powder Studiesmentioning

confidence: 69%

Section: Explosive Powder Studiesmentioning

confidence: 81%

Section: Explosive Powder Studiesmentioning

confidence: 99%

Section: Explosive Powder Studiesmentioning

confidence: 99%

See 3 more Smart Citations

The effects of electrically exploding gold bridgewires into inert and explosive powder beds

Rae

Rettinger

2021

Shock Waves

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A miniature ionization probe technique using a multilayer circuit board for the study of explosive phenomena in primary and secondary explosives

Spear¹,

Bentley²,

Wolfson³

1983

Combustion and Flame

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Finding the “lost-time” in detonator function

Smilowitz

Remelius

Suvorova

et al. 2019

Applied Physics Letters

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Exploding bridgewire (EBW) detonators were invented during the Manhattan Project over 75 years ago. Initially developed for precise timing and reproducibility, they continue to be used in many applications. Despite widespread use and reliability, their mechanism for function remains controversial. They provide precision timing, yet their function is described in terms of a “lost time” accounting for nearly half of the function time. Buried in understanding the EBW function is the mystery of how an incoherent impulse such as powering a bridgewire yields the coherent energy output of a detonation. Even the general phenomena by which release of chemical energy in a crystalline organic explosive becomes associated with the sonic plane of a steady detonation wave remain uncertain. Here, we investigate the EBW function with a suite of diagnostics and show that stationary heating occurs during the “lost-time.” We use x-ray radiography to observe the propagation of a shock wave from bridgewire vaporization and establish that the origin of the radially emanating detonation wave is spatially separated from the initial shock. Utilizing the observed temperature as a boundary condition in our explosive response models yields a thermal ignition consistent with the “lost-time” and detonation location consistent with previous work. With these results, we define a direct thermal initiation mechanism for the EBW function consistent with previous integral observations and explain the displacement of initiation from the bridgewire burst in time and space.

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Characterization of high explosives by observing growth to detonation

Cited by 4 publications

References 2 publications

The effects of electrically exploding gold bridgewires into inert and explosive powder beds

The effects of electrically exploding gold bridgewires into inert and explosive powder beds

A miniature ionization probe technique using a multilayer circuit board for the study of explosive phenomena in primary and secondary explosives

Finding the “lost-time” in detonator function

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