scholarly journals Пороги инициирования и динамические характеристики взрыва для тонких образцов композитов ТЭН-Al при лазерном воздействии

2019 ◽  
Vol 89 (6) ◽  
pp. 912
Author(s):  
Б.П. Адуев ◽  
Д.Р. Нурмухаметов ◽  
Н.В. Нелюбина ◽  
И.Ю. Лисков
Keyword(s):  
Shock Waves ◽  
Neodymium Laser ◽  
Time Shift ◽  
Explosive Decomposition ◽  
Inclusion Concentration ◽  
Sample Density ◽  
Maximal Pressure ◽  
The Times ◽  
Explosive Burning

AbstractIn this paper, we measured thresholds H _cr of explosive decomposition of thin ( h = 1 mm) samples of PETN-Al composites with densities in the range of ρ = 0.9–1.7 g/cm^3 and variations in the concentration of aluminum inclusions in the range of 0.025–1.0 wt % upon exposure to pulses of a neodymium laser (λ = 1064 nm, 14 ns). For each ρ, inclusion concentrations n _opt, at which the threshold for explosive decomposition of H _cr is minimal, are obtained. The velocities of air shock waves (ASWs) were determined depending on sample density ρ, and the times of the start of explosive decomposition were determined depending on the inclusion concentration. The amplitude (in relative units) and time shift of the maximal pressure of an ASW at the piezodetector are determined depending on sample density. It is concluded that the explosion is governed by the SW mechanism at high densities. As sample ρ decreases, the completeness of the explosion increases, with the most likely mechanism for small ρ being explosive burning. The efficiency of explosive decomposition is higher for samples with lower densities.

scholarly journals Assigning the causative lightning to the whistlers observed on satellites

2006 ◽  
Vol 24 (11) ◽  
pp. 2921-2929 ◽  
Author(s):  
J. Chum ◽  
F. Jiricek ◽  
O. Santolik ◽  
M. Parrot ◽  
G. Diendorfer ◽  
...  
Keyword(s):  
Characteristic Time ◽  
Lightning Discharge ◽  
Small Time ◽  
Time Shift ◽  
Propagation Time ◽  
Lightning Detection ◽  
Lightning Discharges ◽  
Whistler Mode Waves ◽  
The Times ◽  
The Individual

Abstract. We study the penetration of lightning induced whistler waves through the ionosphere by investigating the correspondence between the whistlers observed on the DEMETER and MAGION-5 satellites and the lightning discharges detected by the European lightning detection network EUCLID. We compute all the possible differences between the times when the whistlers were observed on the satellite and times when the lightning discharges were detected. We show that the occurrence histogram for these time differences exhibits a distinct peak for a particular characteristic time, corresponding to the sum of the propagation time and a possible small time shift between the absolute time assigned to the wave record and the clock of the lightning detection network. Knowing this characteristic time, we can search in the EUCLID database for locations, currents, and polarities of causative lightning discharges corresponding to the individual whistlers. We demonstrate that the area in the ionosphere through which the electromagnetic energy induced by a lightning discharge enters into the magnetosphere as whistler mode waves is up to several thousands of kilometres wide.

scholarly journals Влияние изменения газодинамической разгрузки на лазерное инициирование композита ТЭН-алюминий

2019 ◽  
Vol 89 (2) ◽  
pp. 174
Author(s):  
Б.П. Адуев ◽  
Д.Р. Нурмухаметов ◽  
А.А. Звеков ◽  
И.Ю. Лисков ◽  
Г.М. Белокуров ◽  
...  
Keyword(s):  
Laser Fluence ◽  
Glass Plate ◽  
External Pressure ◽  
Neodymium Laser ◽  
Aluminum Nanoparticles ◽  
Explosive Decomposition ◽  
Pentaerythritol Tetranitrate ◽  
Theoretical Simulation ◽  
Gas Dynamic ◽  
Dynamic Unloading

AbstractThresholds of explosive decomposition H _cr under irradiation using the first harmonic of a pulsed neodymium laser (14 ns) are experimentally determined for pentaerythritol tetranitrate (PETN) with aluminum nanoparticles (100 nm) at concentrations ranging from 0.05 to 1 wt %. Amplitudes of optoacoustic signals are measured versus concentrations of impurities in the sample at a fixed laser fluence. The experiments are performed in two regimes. In the first one, the irradiated surface of the sample is covered with a finite-weight glass plate that impedes the gas-dynamic unloading. In the second regime, an external pressure of no less than 10^7 Pa is applied to the glass plate to prevent the gas-dynamic unloading. The interpretation of the experimental effects is proven by the results of theoretical simulation.

Characteristics of the initiation of the explosive decomposition of PETN by the second-harmonic pulsed radiation of a neodymium laser

2015 ◽  
Vol 9 (6) ◽  
pp. 915-920 ◽  
Author(s):  
B. P. Aduev ◽  
D. R. Nurmukhametov ◽  
I. Yu. Liskov ◽  
A. V. Kalenskii ◽  
M. V. Anan’eva ◽  
...  
Keyword(s):  
Second Harmonic ◽  
Neodymium Laser ◽  
Explosive Decomposition

The Eclipsing Binary WX Eridani

1979 ◽  
Vol 46 ◽  
pp. 385
Author(s):  
M.B.K. Sarma ◽  
K.D. Abhankar
Keyword(s):  
Light Curve ◽  
Spectral Type ◽  
Orbital Period ◽  
Primary Component ◽  
Light Curves ◽  
Absorption Feature ◽  
Primary Star ◽  
Eclipsing Binary ◽  
The Times ◽  
Phase Angles

AbstractThe Algol-type eclipsing binary WX Eridani was observed on 21 nights on the 48-inch telescope of the Japal-Rangapur Observatory during 1973-75 in B and V colours. An improved period of P = 0.82327038 days was obtained from the analysis of the times of five primary minima. An absorption feature between phase angles 50-80, 100-130, 230-260 and 280-310 was present in the light curves. The analysis of the light curves indicated the eclipses to be grazing with primary to be transit and secondary, an occultation. Elements derived from the solution of the light curve using Russel-Merrill method are given. From comparison of the fractional radii with Roche lobes, it is concluded that none of the components have filled their respective lobes but the primary star seems to be evolving. The spectral type of the primary component was estimated to be F3 and is found to be pulsating with two periods equal to one-fifth and one-sixth of the orbital period.

Investigation of shock-wave deformation history from recovered structure

1986 ◽  
Vol 44 ◽  
pp. 434-435
Author(s):  
M.A. Mogilevsky ◽  
L.S. Bushnev
Keyword(s):  
Shock Wave ◽  
Plastic Deformation ◽  
Dislocation Density ◽  
Shock Waves ◽  
Shock Front ◽  
Single Crystals ◽  
Residual Deformation ◽  
Deformation Structure ◽  
Deformation History ◽  
Deformation Velocity

Single crystals of Al were loaded by 15 to 40 GPa shock waves at 77 K with a pulse duration of 1.0 to 0.5 μs and a residual deformation of ∼1%. The analysis of deformation structure peculiarities allows the deformation history to be re-established.After a 20 to 40 GPa loading the dislocation density in the recovered samples was about 1010 cm-2. By measuring the thickness of the 40 GPa shock front in Al, a plastic deformation velocity of 1.07 x 108 s-1 is obtained, from where the moving dislocation density at the front is 7 x 1010 cm-2. A very small part of dislocations moves during the whole time of compression, i.e. a total dislocation density at the front must be in excess of this value by one or two orders. Consequently, due to extremely high stresses, at the front there exists a very unstable structure which is rearranged later with a noticeable decrease in dislocation density.

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