Physical foundations for approximately modeling explosions with ejecta

Various cases of exact and approximate similarity are examined for underground explosions with the ejection of earth material. Attention is given to a contradiction between current representations of the similarity law and the reduced data of large-scale experiments. A refined phenomenological theory is presented. A possible similarity of the ejecta is shown for identical materials. These representations are in agreement with more precise reductions of experimental data. Convenient dimensionless parameters are presented which are the basis for an approximate method for modeling large-scale explosions under laboratory conditions.All-Union Scientific Research Institute for Technical Physics, Chelyabinsk. Translated from Fizika Goreniya i Vzryva, No. 1, pp. 123–130, January–February, 1995.     

Trench formation in group explosions with linear charge distribution

Using the laboratory-modeling method developed at the All-Russian Scientific-Research Institute of Engineering Physics, group explosions for the creation of long trenches (canals) are investigated. The minimum canal cross section and its other dimensions are obtained as a function of the basis parameters of the explosion. Conditions for the creation of canals with minimum fluctuation of the profile over the trench length are found, criteria of economic efficiency are derived, and a method is given for choosing the explosion parameters so as to create a canal of specified cross section with minimum expenditure of explosives. The results of the model experiments are compared with the trench dimensions in the Baggi (USA) and T-II (Russia) nuclear explosions.All-Russian Scientific-Research Institute of Engineering Physics. Translated from Fizika Goreniya i Vzryva, Vol. 31, No. 3, pp. 76–82, May–June, 1995.     

Self-ignition of dusty media

Thermal explosions of gaseous media containing inert dust particles are examined. The critical conditions for a thermal explosion are determined using integral manifolds. An asymptotic formula for calculating the critical conditions for thermal explosions with an autocatalytic combustion reaction is obtained.Samara. Translated from Fizika Goreniya i Vzryva, Vol. 29, No. 3, pp. 133–136, May–June, 1993.     

Optimal parameters of borehole charges

Experimental data on full-scale borehole-charge explosions are outlined, with a view to establishing the optimal relation between the basic sinkhole parameters and the charge elongation coefficient. It is shown that the results of full-scale explosion are in good agreement with laboratory data.Krasnodar. Translated from Fizika Goreniya i Vzryva, Vol. 28, No. 4, pp. 127–129, July–August, 1992.     

The Concept of Chamber Design for Explosive Thermonuclear Fusion Energetics

The possibility of realizing the solution of mankind's energy problem by the explosive thermonuclear fusion method that was proposed by Academician A. D. Sakharov is assessed. The essence of the method consists of the use of the energy of low–power thermonuclear explosions performed cyclically in stationary explosion–proof chambers equipped with a means for selection and utilization of the thermal energy of the explosion. Here the basic problem is to design airtight chambers capable of withstanding multiple thermonuclear explosions whose power is equal to 10—25 ktons of TNT. The available data on this problem are examined. The concept of designingreliable explosion–proof chambers for the solution of the indicated problem is formulated.     

Experimental investigation of craters generated by explosions of underwater surface charges on sand

The paper presents the results of laboratory investigations of the shape and sizes of craters generated by explosions of underwater surface charges on sand. Curves of the main crater parameters versus water depth are plotted. An explanation is given for the differences in crater parameters due to changes in the water depth. The existence of an optimum depth at which the crater parameters are maximized is also explained.Translated from Fizika Goreniya i Vzryva, Vol. 32, No. 3, pp. 122–125, May–June, 1996.     

Explosive Initiation of Creative Processes in Nature

The paper deals with the construction of explosive–fill dams, of which Academician M. A. Lavrent'ev was an enthusiast. His contribution to the construction of the Alma–Ata mud dam is described. The experience of industrial explosions is used to show the possibility of including the potential of nature in human creative activity by means of explosion energy. Large–scale processes of rocksliding and formation of long–range rock avalanches produced by man–made and natural factors are considered. The development of a spontaneous landslide is described using a model of a rigid body with inhomogeneities. As a result, a unified approach to natural and man–made relief–forming processes is proposed. Recommendations for prediction and prevention of disastrous landslides are formulated.     

Generation of Electric and Magnetic Fields by Air, Surface, and Underground Explosions

Results of an experimental investigation of electric and magnetic fields generated by explosions of charges of a chemical high explosive in the frequency range of 0–10 kHz are presented. It is shown that the characteristics of signals of the electric and magnetic fields registered in explosions of highexplosive charges in air, on the ground surface, and in underground explosions are significantly different.     

Possible Failure Mechanism of Cavities Produced at Depth in a Rock Salt Massif by an Explosion

Experimental and analytical studies were performed of the deformation and failure of cavities produced for condensed gas storage at depths of 920–1100 m in a salt massif by 15 nuclear explosions. From the results of the studies a method is proposed to preserve the volume of the cavities after explosion by producing a back pressure in them.     

Shockwave attenuation in gas suspensions

Conclusions An approximate solution permitting computation of attenuation of a shock of initially a step profile to equilibrium intensity during propagation in a gas suspension is obtained in this paper. Since a shock generated by explosions of HE charges, gas and dust clouds, are characterized, as a rule, by a pressure drop behind the front, then the proposed solution permits making conservative estimates about their destructive action.Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 27, No. 1, pp. 130–136, January–February, 1991.     

A method of modeling large cratering explosions

Summary Modeling a cratering explosion has made it possible to investigate the dependence of the crater radius on the depth of the charge and the energy of the gas in the cavity. The empirical formula thus obtained is in satisfactory agreement with the results of test explosions in alluvium and loam over a broad interval of charge weights (from 80 kg to 450 t). The model and full-scale experiments are also in agreement with respect to their kinematic characteristics.The role of the gravity field in the cratering process has been clearly established and a corresponding method of calculating the energy of the explosion at different charge depths is proposed.The possibility of modeling a cratering explosion with respect to its kinematic parameters suggests new means of solving a whole series of engineering problems involving the explosive displacement of soil masses.Fizika Goreniya i Vzryva, Vol. 3, No. 1, pp. 119–127, 1967     

Study on the Si–Si Vibrational States of the Near Surface Region of Porous Silicon

The Si–Si vibrational states near the surface region of porous silicon has been characterized using Fourier Transform Infrared Spectroscopy (FTIR) due to its enlarged surface area. By means of anodic etch and oxidization experiments, two Si–Si vibration modes of porous silicon have been identified as near the surface regions and in the bulk, respectively. The intensity of absorption peak at 620 cm^–1, which originates from the Si–Si bonds vibrations on the surface and near surface regions of porous silicon, is found to vary depending on the length of etch and degree of oxidation of porous silicon, which exists before etching and is recovered again after fully oxidation. The peak of 610 cm^–1 doesn't change throughout the oxidation experiment, and to be assigned for Si–Si bond vibrations in the bulk. With an extra irradiation of Nd:Yag laser on the PS sample the Raman and FTIR spectra reveal a red shift. These results can give an interpretation to explain the different phenomenon of Si–Si vibrations of Raman and FTIR spectroscopy.     

Vibration sensitivity of solid explosives

The vibration sensitivity of solid explosives has been studied and is found as a function of the explosive parameters and the type of roller devices used to model various deformation conditions. A method is proposed for determining the vibration sensitivity from the probability of explosions as a function of the vibration parameters, experimental data on the sensitivity of some explosives and on the stresses in specimens are given, and a mechanism of initiating an explosion under cyclical loads is considered.Samara State Technical University, Samara 443010. Translated from Fizika Goreniya i Vzyrva, No. 1, 97–103, January–February, 1995.     

Electropolymerization of aniline on carbonized polyacrylonitrile aerogel electrodes: applications for supercapacitors

Polyaniline was electrochemically synthesized on carbon polyacrylonitrile aerogel electrodes for use as active material in supercapacitor devices. Electrochemical characterization was performed by cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and charge–discharge experiments in aqueous medium. Two types of electrochemical phenomenon were observed; the first is based on electrostatic energy storage in the double layer at the interface solution/carbon polyacrylonitrile (PAN) aerogel, the other is associated with the redox processes in polyaniline, for which the faradaic charge depends on the potential range. The performance of the supercapacitor was tested for capacity, energy and power density and self-discharge. Specific capacitance as high as 230 F g^–1 was reached. A symmetrical supercapacitor showed good cyclability (over 3000 cycles) during repeated charge–discharge cycles. The results are very promising and demonstrate the viability of a symmetric supercapacitor based on carbon PAN aerogel covered by an electronically conducting polymer.     

Initiation of primary explosives by electron pulses of microsecond duration

The explosive decomposition of initiating explosives, namely, lead, silver, cadmium, and thallium azides, potassium picrate, lead styphnate, mercury fulminate, and tetrazene, on irradiation by electron pulses of various durations was studied. The critical parameters of electron pulses that initiate specimen explosions are determined. The critical energy density in pulses of microsecond duration is shown to be less than that in pulses of nanosecond duration. A decrease in the temperature of irradiated specimens to –80°C does not cause changes in the critical-pulse parameters. Explosion initiation by an electron pulse is regarded as a result of concentration of electronic excitations and initiation-spot formation.Translated from Fizika Goreniya i Vzryva, Vol. 32, No. 3, pp. 113–118, May–June, 1996.     

Deformation of Block Environments in Underground Nuclear Explosions

The main regularities in the movement of structural blocks of various scales due to underground nuclear explosions were determined in unique experiments performed in tunnels and on the surface of a mountain massif at the Semipalatinsk test site. The spatial–temporal movement of block structures is alternating in nature. The amplitudes of differential block movements far exceed the displacements in the explosion seismic wave. The linear dimensions of blocks of various scales and their explosioninduced differential displacements are determined.     

Drag of nonspherical particles in a flow behind a shock wave

The early stage of velocity relaxation of nonspherical particles in a flow behind an incident shock wave is considered by the method of multiframe shadowgraphy. A procedure of processing the data on the motion of a free body for determining its acceleration is proposed; in combination with the diagnostic method used, the procedure forms something like a noncontact aerodynamic balance. Novel data on the drag of bodies of irregular shape in a flow behind a shock wave with Mach numbers of 0.5–1.5 and Reynolds numbers of 10⁵ typical of dust explosions are obtained. It is found that the values of drag of a nonspherical bluff body and a sphere under these conditions are similar and exceed the drag of a sphere in a steady flow by a factor of 2 to 3.Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 1, pp. 81–88, January–February, 2005.     

Fires caused by nuclear explosions and their consequences

The intensity of fires caused by nuclear explosions and leading to injection of considerable amounts of smoke and black carbon to the atmosphere has been estimated. Estimation is based on the studies of the problem of nuclear winter — strong cooling of the Earth's surface owing to solar-radiation screening by the smoked atmosphere after wide-scale nuclear war.Translated from Fizika Goreniya i Vzryva, Vol. 32, No. 5, pp. 116–121, September–October, 1996.     

XPS analysis of wet chemical etching of GaAs(110) by Br2–H2O: comparison of emersion and model experiments

We have applied photoelectron spectroscopy to investigate the surface composition after different surface treatments involving Br₂–H₂O mixtures in order to study wet chemical etching. Emersion experiments from Br₂–H₂O solution are compared with model experiments, in which Br₂–H₂O adsorbate and coadsorbate mixtures react with clean GaAs(110) surfaces. Our results indicate that Ga- and As-bromides formed initially are hydrolyzed to form the respective oxides. Without addition of Br₂, only slight oxidation of the surface takes place. There is an enrichment of Ga due to loss of As both in adsorption as well as in emersion experiments. Since in emersion experiments only a final situation is analyzed, the relative influence of surface reactivity and subsequent solvation effects cannot be distinguished easily, while model experiments give clear information on reaction products formed intermediately. However, model experiments differ in environment and temperature from the real solid–liquid interface. The presented results demonstrate that a combination of emersion and model experiments provide valuable insight into the mechanism of wet chemical etching on a microscopic level.