Formation of dense plasma on the surface of a stainless steel conductor in superstrong magnetic fields

In experiments on the GIT-12 megaampere generator, the characteristics of conductors made of AISI 321 stainless steel were investigated in the microsecond regime of increasing superstrong magnetic fields. In this regime, a skin explosion of the conductor material takes place with the formation of a dense plasma and its expansion into the interelectrode gap of the vacuum transmission line. The values of the characteristic magnetic field B0 = 100 T are determined, above which there is the effect of nonlinear diffusion of the magnetic field into the conductor, and the critical magnetic field BCT ≅ 260 T, the excess of which leads to the formation of dense plasma on the surface of the massive conductor. A method is proposed for increasing the critical magnetic field on the surface of a conductor up to 1.5 times by choosing the optimal thickness of the conducting surface, and criteria for its determination are given. The effect of increasing the critical magnetic field on the surface of a two-layer sample and creating a pressure in the Mbar range until the moment of formation and expansion of explosion products of an inner conductor with high conductivity has been tested.

Basic calculation methods of investigation of circumstances and mechanism of man-made explosions

The article purpose is to analyze the danger of man-made explosions and provide calculation methods for determining the mechanism of the occurrence of an explosion during forensic examinations of the study of the circumstances and mechanism of man-made explosions. The relevance of the article is caused by the fact that present-day production and everyday life cannot dispense with the usage of combustible and explosive substances. The particular attention to be paid to emergency prevention related to explosives, as well as the research to determine the mechanism of man-made explosions. The research on the mechanism of man-made explosions will make it possible to determine the technical cause of their occurrence, to analyze for what reason and for whose fault the event occurred, and also what measures should be taken to minimize the likelihood of such situations occurence. It is noted that in order to obtain reliable conclusions about the mechanism of man-made explosions, it is necessary to use scientifically based methods and methodologies allowing us to assess the extent of destruction. The degree of destruction of surrounding building structures and harm to people depends on overpressure caused as the result of a significant expansion of the explosion products and their spread to all directions from the center of explosion. The most frequent causes of explosions in the explosive object are: destruction and damage to production tanks, equipment and pipelines; deviation from production regulations (excess pressure and temperature of equipment operating mode), low-quality control of equipment and work while conducting require work, and untimely or poor-quality maintenance of technological equipment. The main calculation methods for the research of the man-made explosions in open areas, indoors, and limited space are given, which will allow to systematize the research process and analyze the flow of explosions in specific situations, and to establish a mechanism for their occurrence when conducting forensic examinations of the circumstances and mechanism of man-made explosions.

Assessment of the Parameters of a Shock Wave on the Wall of an Explosion Cavity with the Refraction of a Detonation Wave of Emulsion Explosives

At present, studying the parameters of shock waves at pressures up to 20 GPa entails a number of practical difficulties. In order to describe the propagation of shock waves, their initial parameters on the wall of the explosion cavity need to be known. With the determination of initial parameters, pressures in the near zone of the explosion can be calculated, and the choice of explosives can be substantiated. Therefore, developing a method for estimating shock wave parameters on an explosion cavity wall during the refraction of a detonation wave is an important problem in blast mining. This article proposes a method based on the theory of breakdown of an arbitrary discontinuity (the Riemann problem) to determine the shock wave parameters on the wall of the explosion cavity. Two possible variants of detonation wave refraction on the explosion cavity wall are described. This manuscript compares the parameters on the explosion cavity wall when using emulsion explosives with those obtained using cheap granular ANFO explosives. The detonative decomposition of emulsion explosives is also considered, and an equation of state for gaseous explosion products is proposed, which enables the estimation of detonation parameters while accounting for the incompressible volume of molecules (covolume) at the Chapman–Jouguet point.

Ecotoxicity Assessment of the Industrial Explosives Explosion Products

The statistics is presented in the article concerning the industrial explosives consumption in the world and in the Russian Federation, based on which it is possible to estimate the scale of emission of toxic gaseous explosion products into the environment. The mechanism of formation of gaseous explosion products depending on the oxygen balance of the mixed ammonium nitrate explosive is briefly outlined. In the methodological part of the work, an overview is made related to some computational methods for determining the qualitative and quantitative compositions of gaseous explosion products of industrial explosives based on ammonium nitrate. The main regularities of the influence of physical and physicochemical factors surrounding the charge of an industrial explosive on the formation of toxic gaseous explosion products are described. Computational part of the work is a description of the calculation parameters and the used software packages Shock and Detonation and Real, and the tabulated results of the calculations in comparison with the experimental data obtained from the literature sources. When discussing the results, it is shown that using theoretical calculation methods, only an approximate estimate (with an error of more than 32 %) of the qualitative and quantitative compositions of gaseous explosion products is possible. Doubt is expressed about the conversion coefficient of the concentration of nitrogen oxides to the conditional carbon monoxide-6.5, which is adopted for use in the calculations without substantiating the reasons. It is concluded that only computational methods for determining the composition of gaseous explosion products are available, the results of which are far from reality, and experimental methods are only partially close to the real conditions, respectively, it is required to develop new computational methods. It is noted that the prospect for the development of this topic is the creation of a new computational software package based on the experimental data.

Equations of state for detonation products of explosives

A comparative analysis of the equations of state for the detonation products of condensed explosives, which are most used in solving problems of the mechanical action of an explosion, is presented. For the most widespread (cited) equations of state of explosion products in the form of JWL, methods and algorithms are proposed for determining the correctness of specifying the coefficients included in this equation. To solve radiation-gasdynamic problems, including multicomponent mixtures, a version of the thermal equation of state of explosion products in the form of JWL is proposed, and a constant set for the most common explosives is recommended.

MEASUREMENT OF EXPLOSION AFTERBURNING FIREBALL TEMPERATURE BY DUAL-BAND PHOTODIODE

A temperature of terminal combustion (afterburning) of thermobaric mixtures is an important parameter of explosion effectiveness. The paper revews typical methods of spectroscopy, optical pyrometry, and thermovision for measuring the terminal combustion temperature of a fireball of explosion products. A method of continuous measurement by a dual-band photodiode operating on 400-1100 nm and 1000-1800 nm is presented. Method’s high time resolution allows for the identification of rapid temperature changes resulting, for example, from the passage of a reflected blast wave through the fireball. The main assumptions of the method, the results of preliminary measurements and their comparison with spectrometric measurements for the same charges are presented. The measurements were carried out for mixtures of ammonium nitrate (V) with aluminum and with PAM.

Estimation of TNT equivalent of detonating explosive gas

The purpose of the study was to compare the genuine work of explosion of detonating gas and trinitrotoluene during their reaction in the form of detonation. The comparison was done in the framework of the concept of the strength of the explosives as the ability of their degradation products to perform work under isentropic expansion, starting from the initial state in which the products of instant explosion are located. The study introduces the calculation data using the gas equation for products of detonation of a detonating gas at different initial pressures, and the Johns-Wilkins-Lee (JWL) equation for trinitrotoluene. With a high-explosive effect characterized by a final pressure of the order of a tenth of a megapascal, in which the explosion products are still able to perform the required form of work, the relative TNT equivalent of detonating gas will rise from about 50% to 110% with an increase in the initial pressure of the gas charge from a normal value to one megapascal.