X-ray imaging and 3D reconstruction of in-flight exploding foil initiator flyers

Willey, Trevor M.; Champley, Kyle; Hodgin, Ralph; Lauderbach, Lisa; Bagge‐Hansen, Michael; May, Chadd; Sanchez, Nathaniel; Jensen, Brian J.; Iverson, A. J.; Buuren, T. van

doi:10.1063/1.4953681

Cited by 42 publications

(20 citation statements)

References 13 publications

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“…Time-resolved small-angle x-ray scattering (TR-SAXS) and scatter beam imaging (SBI) were performed at the Advanced Photon Source, Argonne National Laboratory, at the Dynamic Compression Sector 35-ID-B [9,10,12,13], and at Sector 32-ID-B [14][15][16] in the LLNL detonation tank [10]. Detonations were fired in the vacuum vessel at < 200 mTorr, with Kapton TM (polyimide) windows sealing the vacuum and providing x-ray transmission.…”

Section: Methodsmentioning

confidence: 99%

Observation of Variations in Condensed Carbon Morphology Dependent on Composition B Detonation Conditions

Hammons

Nielsen

Bagge‐Hansen

et al. 2020

Propellants Explo Pyrotec

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Carbon particulates generated during detonation depend upon high explosive type, composition, and detonation conditions. Although explosive composition greatly affects particulates, the focus of this work is on how detonation geometries that induce much higher temperatures and pressures in the high explosive lead to differing particulate morphologies. In this study, two geometries were used: Detonations were initiated in Composition B cylinders at one end in conventional detonations and initiated at both ends to produce colliding detonations. Each of these detonations was observed on the sub‐μs timescale using fast radiography capturing images of the front moving through the cylinder, and colliding detonation fronts in real‐time. These imaging experiments were complemented with time‐resolved small‐angle x‐ray scattering (SAXS) experiments that were able to observe and determine the varying condensed carbon morphologies at different locations and times in each detonation. The detonations could be timed in such a way that the spatial and temporal dependence of the carbon morphology could be superimposed onto radiography images collected at the same point in time. The complementary approach is able to show that the carbon condensates are much larger when formed in the elevated temperature and pressure conditions near the location of colliding detonation fronts. Thermochemical modeling suggests that these larger particulates form either in the diamond phase or on the liquidus line of the carbon phase diagram. The increase in size observed by SAXS may correlate well with the increased residence time deeply in the diamond phase. These particulates can be described as nano‐sized phases with some surface texture or otherwise near‐surface intra‐particle heterogeneity.

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Section: Methodsmentioning

confidence: 99%

Observation of Variations in Condensed Carbon Morphology Dependent on Composition B Detonation Conditions

Hammons

Nielsen

Bagge‐Hansen

et al. 2020

Propellants Explo Pyrotec

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“…This system facilitates detailed investigations of short length and time scale phenomena using high‐speed spectroscopic and imaging techniques that observe explosive microstructures during shock initiation . These thin‐film shock drives are comparable to exploding foil initiators in shock strength and duration which further facilitates direct comparison between other experimental methods and simulation .…”

Section: Introductionmentioning

confidence: 99%

Shock Initiation Microscopy with High Time and Space Resolution

Bassett

Johnson

Salvati

et al. 2020

Propellants Explo Pyrotec

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We describe studies of shock initiation and shock‐to‐detonation transitions in energetic materials using a tabletop shock compression microscope with nanosecond time resolution and micrometer spatial resolution. Planar input shocks with durations of 4–20 ns are produced using 0–4.5 km/s laser‐launched flyer plates. Emphasis is on measurements of temperature, velocities, pressure, and microstructure using photon Doppler velocimetry (PDV), optical pyrometry and high‐speed videography. Techniques are discussed for fabricating disposable shock target arrays of tiny plastic‐bonded explosives (PBX), liquid and powder explosives, and single‐crystal explosives for high‐throughput studies. Optical temperature measurements of shocked triaminotrinitrobenzene (TATB) are discussed. Since TATB is yellow, we developed methods to correct for the blue absorption to obtain more accurate temperatures. Hot spots in shocked polymer‐encased HMX (octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine) crystals are observed in real‐time, showing a hot spot produced in a collapsing void that ignites a deflagration. Despite the small dimensions of our explosive charges (typically 1 mm diameter and 250 μm length), we produced reproducible detonation states in solid and liquid explosives using short‐duration shocks near the von Neumann spike (VNS) pressure. We show the VNS pressure is associated with a transition to high‐efficiency gas production from the explosives. In studies of NM, prior to detonation, we see reaction originating at hot spots which coalesce to form a superdetonation.

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“…Furthermore, the performances of the micro-plasma generator were characterized by testing its ability to drive the Kapton flyer with the thickness of 30 μm. A short current pulse was applied on the plasma generator, causing a fast explosion of the bowtie bridge (0.4 × 0.4 mm), which in turn compelled the flyer to accelerate to a velocity up to several kilometer per second [ 33 – 35 ]. And the velocity of the flyer was recorded by a photonic Doppler velocimetry (PDV).…”

Section: Experimental Methodsmentioning

confidence: 99%

Energetic Al/Ni Superlattice as a Micro-Plasma Generator with Superb Performances

et al. 2018

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In this study, energetic Al/Ni superlattice was deposited by magnetron sputtering. A micro-plasma generator was fabricated using the energetic Al/Ni superlattice. The cross-sectional micro-structure of the energetic Al/Ni superlattice was scanned by transmission electron microscopy. Results show that the superlattice is composed of Al layer and Ni layers, and its periodic structure is clearly visible. Moreover, the bilayer thickness is about 25 nm, which consists of about 15 nm Al layer and 10 nm Ni layer. The micro initiator was stimulated using a 0.22 μF capacitor charged at 2900–4100 V. The electrical behaviors were investigated by testing the current-voltage waveform, and the plasma generation was explored by ultra-high-speed camera and photodiode. The integrated micro generator exhibited remarkable electrical exploding phenomenon, leading to plasma generations at a small timescale. The plasma outputs reflected by flyer velocities were superior to that with a much thicker bilayer of 500 nm Al/Ni multilayer. The higher flyer velocity combined with Gurney energy model confirmed the chemical reaction of the Al/Ni superlattice structure contributed to plasma production in comparison with the Al/Ni multilayers. Overall, the energetic Al/Ni superlattice was expected to pave a promising avenue to improve the initiator efficiency at a lower energy investment.

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X-ray imaging and 3D reconstruction of in-flight exploding foil initiator flyers

Cited by 42 publications

References 13 publications

Observation of Variations in Condensed Carbon Morphology Dependent on Composition B Detonation Conditions

Observation of Variations in Condensed Carbon Morphology Dependent on Composition B Detonation Conditions

Shock Initiation Microscopy with High Time and Space Resolution

Energetic Al/Ni Superlattice as a Micro-Plasma Generator with Superb Performances

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