Initiation of lead azide with laser radiation

Aleksandrov, Evgenii; Voznyuk, A.

doi:10.1007/bf00742955

Cited by 21 publications

(34 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In the volume of such an inhomogeneity and its neighborhood, a hot spot arises, leading to fast decomposition, ignition, and detonation of the HE. The basic reaction that ensures thermal acceleration of the process is given by the expression [10] N 3 + N 3 = 3N 2 + Q, (1) where N 3 are radicals and Q = 1-2 kJ/g (about 10 eV per act).…”

Section: Status Of the Issue And The Formulation Of The Problemmentioning

confidence: 99%

“…Results of measurements of the IETs under various conditions of exposure of HEs to a laser pulse were used to develop a thermal hot-spot model for the initiation of heavy metal azides (HMAs) [1,2,[5][6][7], which was considered conventional in 1980-1990 [7][8][9]. According to this model, the laser pulse energy is localized at optical inhomogeneities, which are inevitably present in the volume of a HE transparent to laser radiation.…”

Section: Status Of the Issue And The Formulation Of The Problemmentioning

confidence: 99%

“…Samples of lead azide [Pb(N 3 ) 2 ], silver azide (AgN 3 ), and thallium azides (TlN 3 ) were synthesized using the procedure of [1,15] and had the form of loose powders, pressed (a pressure of 10 9 Pa and a density of 4.1 g/cm 3 ) pellets 2-3 mm in diameter and 100-500 µm thick, AgN 3 macrocrystals of size 1 × 1 × 0.4 mm, and AgN 3 filamentary crystals of size 0.1×0.05×5 mm. The samples were set up in special assemblies (Fig.…”

Section: Experimental Techniquementioning

confidence: 99%

“…It is known [1][2][3][4] that one of the main parameters indicating a particular mechanism of initiation of high explosives (HEs) is the ignition energy threshold (IET). Results of measurements of the IETs under various conditions of exposure of HEs to a laser pulse were used to develop a thermal hot-spot model for the initiation of heavy metal azides (HMAs) [1,2,[5][6][7], which was considered conventional in 1980-1990 [7][8][9].…”

Section: Status Of the Issue And The Formulation Of The Problemmentioning

confidence: 99%

See 3 more Smart Citations

Kinetics and Mechanism of Explosive Decomposition of Heavy Metal Azides

Korepanov

Лисицын

Олешко

et al. 2006

Combust Explos Shock Waves

View full text Add to dashboard Cite

The explosive decomposition of heavy metal azides initiated by a laser pulse was studied experimentally over a broad range of action levels (from the threshold values to those exceeding the threshold ignition energy by a factor of 100) and in the time interval including the induction period, and rapid explosive decomposition, and the expansion of detonation products. The explosive glow and expansion dynamics of the decomposition products in air and vacuum were investigated, and the velocities of the explosive decomposition front, the compression pulse, and the expansion of the explosion products were measured. Based on the results obtained, the possibility of the occurrence of preexplosion phenomena is discussed and the mechanism of laser initiation of heavy metal azides is analyzed.

show abstract

Section: Status Of the Issue And The Formulation Of The Problemmentioning

confidence: 99%

Section: Status Of the Issue And The Formulation Of The Problemmentioning

confidence: 99%

Section: Experimental Techniquementioning

confidence: 99%

Section: Status Of the Issue And The Formulation Of The Problemmentioning

confidence: 99%

See 2 more Smart Citations

Kinetics and Mechanism of Explosive Decomposition of Heavy Metal Azides

Korepanov

Лисицын

Олешко

et al. 2006

Combust Explos Shock Waves

View full text Add to dashboard Cite

show abstract

“…Lead azide is characterized by high transparency at a wavelength of 1.06 μm. It is known [8] that PbN 6 initiation by a laser pulse occurs as a result of energy localization on absorbing microscopic inclusions, and the size effect is determined by the laws of light scattering [2][3][4]. A comparison revealed some interesting features.…”

mentioning

confidence: 94%

Size effect in laser-induced initiation of a pyrotechnical composition (ammonium perchlorate and ultrafine aluminum)

Medvedev

Агеева

Tsipilev

et al. 2008

Combust Explos Shock Waves

View full text Add to dashboard Cite

The energy thresholds and ignition delays of pressed samples of a stoichiometric pyrotechnical mixture of ammonium perchlorate and ultrafine aluminum are studied as functions of the diameter of the laser spot created by a millisecond laser pulse. A clearly expressed size effect is found. A characteristic size determining the boundary between the wide and narrow beams of the laser pulse applied is determined. The influence of optical properties of the examined composition on the behavior of the size dependences is discussed. The relation between the nature of the size effect and the laws of light scattering in the volume of powdered pyrotechnical mixtures is considered.Key words: laser radiation, pyrotechnical mixture, size effect, ignition threshold.The size effect (dependence of the threshold energy density on the diameter of the laser beam on the sample surface) in laser-induced initiation of pressed powders of high explosives (HEs) was found in [1] and studied in detail in [2-4] (lead azide) and [5] (PETN). The existence of the size effect is attributed either to the laws of light scattering in the volume of transparent HE powders [2][3][4] or to one of the fundamental characteristics of high explosives, namely, critical diameter of detonation [1,5].There seem to be no publications on size dependences of laser-induced initiation of pyrotechnical mixtures. Following [1-5], we can conclude that size effects are determined by optical, gas-dynamic, and thermophysical characteristics of high explosives in a particular experiment. Therefore, understanding the nature of the size effect can be a key point in understanding the mechanism of initiation as a whole. A conclusion about a rather weak gas-dynamic unloading of the thermal spot in the course of ignition of a mixture consisting of 75% of ammonium perchlorate (AP) and 25% of ultrafine aluminum (UFA) under the action of a wide laser beam was made in [6]. The same feature can be expected for small-size regions as well. At the same 1 Tomsk Polytechnical University, Tomsk 634050, medvedev@tpu.ru. time, the optical characteristics of compositions can be varied within wide limits by adding various reagents or passive absorbing admixtures. Results of such experiments, which are described below, can provide valuable information about the structure and parameters of ignition spots.We considered an AP-UFA composition prepared by the method described in [6]. Charges of ≈10 mg were placed into an assembly, were pressed by a hydraulic press with a pressure of 4 · 10 7 N/m 2 to a density of ≈1.5 g/cm 3 , and were irradiated in a compressed state (Fig. 1). The reflection index at the laser radiation wavelength was measured in some experiments by a light-integrating sphere coated inside by BaSO 4 ; the value measured was ≈0.35. The light-integrating sphere had three orifices (windows): two of them were aligned along the axis at diametrically opposing ends of the sphere, and the third window was aligned at an angle of 45 • to the axis. Laser radiation with a wavelength of 1.06 μm...

show abstract

Review of Laser Initiation

Ahmad¹,

Cartwright²

2014

Laser Ignition of Energetic Materials

View full text Add to dashboard Cite

The first experiments with laser initiation of energetic materials as an alternative to standard electrical initiation were performed in the early 1960s. This was a direct consequence of the success of laser beams in cutting through steel and other metal sheets by rapidly melting them. Most of the lasers used were in the red to infrared region, since it was thought that direct heating was the optimum method to achieve the rapid combustion needed for typical propellant ignition. Looking at the scattering of laser radiation in Raman spectrometry, the closer the radiation wavelength is to the molecular vibration frequencies, the stronger the inelastic scattering is, and the more energy is transferred to molecular vibrations; the criteria for an increase in temperature leading to ignition.Later work used lasers to initiate secondary high explosives directly, thus eliminating the need for highly sensitive primary explosives. The experimental arrangement for this study is shown in Figure 2.1. Note the advantage of not having a very sensitive primary explosive, so that the chances of accidental initiation are very much reduced.Laser-initiated field guns started to be tested by the US army in the early 1990s, with the Nd/Glass laser operating at 1.05 μm being the one of choice because of its small dimensions, ruggedness, long life and low cost. The object of these preliminary trials was to initiate the gunpowder booster directly without using the standard, percussion-sensitive military M82 primer. This wavelength was also very adaptable, since it could be transmitted over considerable distances by high purity silica optical fibres, with very little loss due to radiation absorption. Simple use of splitter systems in the optical fibres enabled a number of initiation points to be simultaneously initiated, giving an optimized burn within a single propellant charge. Fibre optic transmission of the laser beam also enabled multiple charges to be initiated simultaneously from a single firing command. This latter has a distinct attraction for quarrying operations if delay detonators can be initiated.A number of prototype guns using laser initiation have been demonstrated in the early 21st century, but regular operation has not been implemented. The Crusader SPH XM2001Laser Ignition of Energetic Materials, First Edition. S Rafi Ahmad and Michael Cartwright.

show abstract

Initiation of lead azide with laser radiation

Cited by 21 publications

References 3 publications

Kinetics and Mechanism of Explosive Decomposition of Heavy Metal Azides

Kinetics and Mechanism of Explosive Decomposition of Heavy Metal Azides

Size effect in laser-induced initiation of a pyrotechnical composition (ammonium perchlorate and ultrafine aluminum)

Review of Laser Initiation

Contact Info

Product

Resources

About