Laser Initiation of the Decomposition of Energetic Polymers: Shock Wave Formation

Ben-Eliahu, Yeshayahu; Haas, Yehuda; Welner, Shmuel

doi:10.1021/j100016a042

Cited by 26 publications

(31 citation statements)

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“…8 given this substitution [209,210]. BenEliahan et al [203] included the energy released by the thermal decomposition, E th , of their glycidyl azido polymer in addition to the laser irradiation energy. These energy values will be influenced by the area irradiated and the volume of polymer ablated, which are listed in Table 4.…”

Section: Resultsmentioning

confidence: 99%

“…This is probably due to the incomplete decomposition of the polymer. To avoid this kind of contamination in microfabrica- The ejected plume has been compared to a microexplosion that produces shock waves in the surrounding gaseous media which have been used to classify the explosion and discuss the released energy [201][202][203]. The observed shock waves resemble explosively formed blast waves, which can be analyzed with point blast theory or may necessitate the use of a theory that includes the source mass of the explosion close to the polymer surface.…”

Section: Introductionmentioning

confidence: 99%

“…The rate of the blast wave propagation is used to classify it as either a weak, intermediate or strong blast wave. A weak blast wave travels near to the speed of sound in the surrounding atmosphere [203]. The propagation of a strong blast wave may be analyzed with a few simplifying assumptions concerning the explosive, such as its energy being instantaneously released into the gaseous product, a negligible point mass source of this energy, and a spherical shock occurring in the surrounding atmosphere.…”

Section: Introductionmentioning

confidence: 99%

“…The propagation of a strong blast wave may be analyzed with a few simplifying assumptions concerning the explosive, such as its energy being instantaneously released into the gaseous product, a negligible point mass source of this energy, and a spherical shock occurring in the surrounding atmosphere. With these assumptions, the propagation radius, R, and time, t, may be related for a strong blast wave [203][204][205],…”

Section: Introductionmentioning

confidence: 99%

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Laser Application of Polymers

Lippert

2004

Polymers and Light

148

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Laser ablation of polymers has been studied with designed materials to evaluate the mechanism of ablation and the role of photochemically active groups on the ablation process, and to test possible applications of laser ablation and designed polymers. The incorporation of photochemically active groups lowers the threshold of ablation and allows high-quality structuring without contamination and modification of the remaining surface. The decomposition of the active chromophore takes place during the excitation pulse of the laser and gaseous products are ejected with supersonic velocity. Time-of-flight mass spectrometry reveals that a metastable species is among the products, suggesting that excited electronic states are involved in the ablation process. Experiments with a reference material, i.e., polyimide, for which a photothermal ablation mechanism has been suggested, exhibited pronounced differences. These results strongly suggest that, in case of designed polymers which contain photochemically active groups, a photochemical part in the ablation mechanism cannot be neglected. Various potential applications for laser ablation and the special photopolymers were evaluated and it became clear that the potential of laser ablation and specially designed material is in the field of microstructuring. Laser ablation can be used to fabricate three-dimensional elements, e.g., microoptical elements.Keywords Laser ablation · Ablation mechanism · Photopolymers · Polyimide · Spectroscopy This was not always true, of course. For many years, the laser was viewed as "an answer in search of a question". That is, it was seen as an elegant device, but one with no real useful application outside of fundamental scientific research. In the last two to three decades however, numerous laser applications have moved from the laboratory to the industrial workplace or the commercial market. Lasers are unique energy sources characterized by their spectral purity, spatial and temporal coherence, and high average peak intensity. Each of these characteristics has led to applications that take advantage of these qualities: -Spatial coherence: e.g., remote sensing, range finding and many holographic techniques. -Spectral purity: e.g., atmospheric monitoring based on high-resolution spectroscopies. -and of course the many other applications in communication and storage, e.g., CDs.All of these high-tech applications have come to define everyday life in the late twentieth century. One property of lasers, however, that of high intensity, did not immediately lead to "delicate" applications but rather to those requiring "brute force". That is, the laser was used in applications for removing material or heating. The first realistic applications involved cutting, drilling, and welding, and the laser was little more advanced than a saw, a drill, or a torch. In a humorous vein A.L. Schawlow proposed and demonstrated the first "laser eraser" in 1965 [4], using the different absorptivities of paper and ink to remove the ink without damaging the und...

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Laser Application of Polymers

Lippert

2004

Polymers and Light

148

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“…7, фронт вторичной ударной волны 3 обладает большей скоростью, чем фронт внешней ударной волны 1, очевидно, вследствие меньшего сопротивления среды, обусловленного как ее разрежением, так и температурным увеличением местной скорости звука. Еще одной особенностью рассматриваемых зависимостей яв-ляется то, что внутренняя ударная волна 4 перемещается с почти по-стоянной скоростью, равной местной скорости звука [30], что позво-ляет оценить температуру среды перед ее фронтом, движущимся со скоростью ~ 2,5 км/с ( для воздуха T ~ 15,5 кК).…”

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Light erosive optical discharges investigation. I. Investigation of radially confined light erosive pulsed optical discharges

Локтионов¹,

Протасов²,

Протасов³

2013

EJSI

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Studies into Laser Ignition of Unconfined Propellants

Ahmad

Russell

Leach

2001

Propellants, Explosives, Pyrotechnics

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Prior to laser ignition tests, spectral absorption properties of three different solid motor propellants were analysed. The extruded double base (EDB) propellant exhibited >95 % absorption over the 250–550 nm wavelength band whereas, the cast double base (CDB) showed similar absorption over a wider band extending between 375–800 nm. The composite sample (CP) showed a uniform spectral absorption at about 90 % over 250–800 nm band. Ignition tests using an average of 500 nm output from an Ar‐ion laser showed that the double base propellants undergo deflagration prior to ignition due to the presence of carbon black material. Within the laser power density range of 24–125 Wċcm−2, the threshold laser energy densities for deflagration and ignition in the double base propellant were found to␣be between 2–2.5 Jċcm−2, and 40–215 Jċcm−2, respectively. No deflagration was observed for the composite propellant, and the threshold ignition energy was found to be within the range, 11–18 Jċcm−2 for the same range of laser power densities. From the ignition map for this propellant, the threshold energy for ignition at this wavelength was found to be approximately 18 Jċcm−2 and was practically independent of laser power density. In the near infrared wavelength (780 nm) the EDB propellant was not readily ignitable due to its comparatively much higher reflectance at this wavelength. The ignition threshold values were found to be between 19–23 Jċcm−2 for a similar power density level. The results indicate that the ignitability of propellants is enhanced through the promotion of deflagration.

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Laser Initiation of the Decomposition of Energetic Polymers: Shock Wave Formation

Cited by 26 publications

References 5 publications

Laser Application of Polymers

Laser Application of Polymers

Light erosive optical discharges investigation. I. Investigation of radially confined light erosive pulsed optical discharges

Studies into Laser Ignition of Unconfined Propellants

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