B. P. Aduev

Effect of laser radiation absorption efficiency on the heating temperature of inclusions in transparent media

The efficiency of light absorption by inclusions of various metals in transparent media is calculated using as an example silver azide, lead, and PETN. It is shown that the absorption efficiency, along with the laser pulse energy density, has a decisive influence on the maximum temperature of heating of the inclusion. Dependences of the maximum heating temperature on the radius of the inclusions are plotted for a pulse duration of 30 ns. Asymptotic expressions are obtained for the dependence of the maximum heating temperature on the pulse duration for an ensemble of inclusions.

Photosensitive material based on PETN mixtures with aluminum nanoparticles

A study was made of the explosion probability and the pressure of explosive decomposition products of PETN samples of density 1.73 g/cm3 with different contents of Al nanoparticles under pulsed laser irradiation (1060 nm; 20 ns). It was experimentally found that the maximum sensitivity and maximum pressure of explosion products are obtained when the mass concentration of nanoparticles is 0.1%. In this case, the mixture sensitivity increases by factor of ≈100 with respect to the samples containing no nanoparticles. The observed effect is due to radiation absorption directly by nanoparticles with the formation of “hot spots,” which initiates an exothermic reaction in the main substance. It is shown that the addition of 0.1% Al decreases the impact sensitivity with respect to the samples without additives. This makes it possible to consider this mixture as a promising material for optical detonators.

Explosive decomposition of PETN with nanoaluminum additives under the influence of pulsed laser radiation at different wavelengths

The results of measurements of the threshold of explosive decomposition of PETN with 0.1 wt % additives of aluminum nanoparticles under the action of the first and second harmonics of a YAG:Nd3+ laser with a pulse duration of 12 ns are presented. A comparison of experimental and theoretical results is performed. It is concluded that the absorption of radiation heats the nanoparticles to form chemical decomposition kernels in the vicinity of the hotspot, so that the initiation of explosive decomposition is not associated with optical breakdown of the sample.

Effect of ultrafine Al-C particle additives on the PETN sensitivity to radiation exposure

The thresholds of explosive decomposition of PETN (pentaerythrite tetranitrate) with the addition of ultrafine Al-C mechanocomposite particles were measured as a function of the concentration of the latter in the experimental samples exposed to laser pulses (1.064 nm, 12 ns). The sample density was 1.73 g/cm3, and the Al-C particle size at the distribution peak was 220 nm. The minimum threshold of explosive transformation corresponding to a 50% probability of explosion with an energy density of 4 J/cm2 was reached at an optimum concentration of the mechanocomposite of 0.1–0.3%. Comparison with experimental data obtained for samples with aluminum nanoparticle additives was performed.

The influence of added aluminum nanoparticles on the sensitivity of pentaerythritol tetranitrate to laser irradiation

The dependences of the probability of the explosion of pentaerythritol tetranitrate with various contents of aluminum nanoparticles on the energy density of initiating laser pulses were obtained. The optimum concentration of nanoparticles, 0.1 wt %, at which sensitivity to laser radiation was maximum was determined.

Role of shock waves in initiating the detonation of pentaerythritol tetranitrate by a pulsed electron beam

The results of measurements of the velocity of shock waves generated in pressed pentaerythritol tetranitrate samples by a pulsed electron beam (0.25 MeV, 15 J/cm2, and 20 ns) and of the velocity of expansion of the explosion products into vacuum are presented. It was demonstrated that, during the interaction of the electron beam with pentaerythritol tetranitrate, it experiences decomposition accompanied by a pressure rise high enough to produce a shock-wave initiation of the sample.

Effect of the initial temperature on the threshold of laser initiation of pentaerythritol tetranitrate seeded with aluminum nanoparticles

The effect of temperature on the threshold of explosive decomposition of pentaerythritol tetranitrate samples with a density of ρ = 1.73 g/cm3 containing 0.1 wt % 100- to 120-nm aluminum particles under the action of laser pulses (λ = 1.06 μm, τ = 20 ns) is examined. A model capable of describing the experimental results is proposed, according to which the explosive decomposition of the samples is associated with the absorption of laser radiation by structural defects of pentaerythritol tetranitrate and aluminum nanoparticles. It is demonstrated that, at 300 K, explosion initiation is largely determined by the heating of aluminum nanoparticles with the formation of chemical decomposition kernels nearby.

Effect of additives of nickel monocarbide nanoparticles on the sensitivity of pentaerythritol tetranitrate to laser irradiation

The probabilities of explosion of pentaerythritol tetranitrate (PETN) doped with various concentrations of nickel monocarbide (NiC) nanoparticles at various fluences of initiating laser radiation were experimentally determined. The possibility of varying the sensitivity of PETN to laser irradiation by adding to it NiC nanoparticles was demonstrated.

Laser Initiation of a Mixture of PETN with NiC Nanoparticles at Elevated Temperatures

The temperature dependence of the probability of the explosion of pentaerythritol tetranitrate (PETN) with an admixture of NiC particles (0.3 wt %) initiated by laser pulses (1064 nm, 20 ns) was studied over the temperature range 295–450 K. At 295–350 K, a weak temperature dependence was observed. The determining contribution to explosion initiation was made by the absorption of laser radiation by nanoparticles. The threshold of explosive decomposition at 295 K decreased by ∼40 times compared with samples free of NiC nanoparticles. Over the temperature range 400–450 K, the threshold of the explosive decomposition of samples containing NiC nanoparticles decreased with the activation energy ∼0.4 eV. A decrease in the threshold of explosive decomposition with a ∼0.4 eV activation energy over the temperature range 340–440 K was also observed for laser action on PETN samples not containing NiC. A hypothesis was suggested according to which the absorption of a light quantum caused the transfer of an electron from the valence band of the crystal to a level in the forbidden band with subsequent thermal positive ion dissociation to the carbocation and NO3 radical.

Pressure of the products of the explosive decomposition of a mixture of pentaerythritol tetranitrate and nickel monocarbide nanoparticles initiated by laser radiation

Relative characteristics of the pressure created by the products of explosive decomposition of a mechanical mixture of pentaerythritol tetranitrate and nickel monocarbide (NiC) nanoparticles upon laser initiation are determined. It is demonstrated that the explosion of the mechanical mixture is caused by the absorption of laser radiation by NiC nanoparticles, a process accompanied by the heating and exothermic decomposition of NiC to the nickel and carbon phases, which, in turn, give rise to the formation of hotspots. The optimal concentration of NiC at which the maximum pressure of the explosion products is achieved is determined.