Electromagnetic Field and Current Waves in a Conductor Compressed by a Shock Wave in a Magnetic Field

A physically correct and mathematically rigorous solution of the problem on the structure of an electromagnetic field formed when a shock wave enters a conducting half–space in a transverse magnetic field is obtained. It is shown that only physically grounded boundary conditions lead to a noncontrovercial pattern of the electromagnetic field and a system of currents in a conductor. The main parameters and characteristic times are found, which determine the structure of current waves in a metal. The solution in the uncompressed region is determined by the parameter R₁ = µ₀₁D²t and that in the compressed region by the parameter R₂ = µ₀₂(D—U)²t (₁ and ₂ are the electric conductivities of the uncompressed and compressed substance, respectively, µ₀ is the magnetic permeability of vacuum, D is the wave–front velocity, U is the mass velocity, and t is the time). The parameter for the compressed substance R ₂ coincides with the parameter obtained previously for the shock–wave dielectric—metal transition; the governing parameter for the uncompressed substance R ₁ is obtained for the first time. The asymptotic solutions of the problem for small and large times and the special case R ₁ = R ₂ considered help in understanding the physical meaning of the solution found.     

Treating ground waters to remove petroleum products — Protecting the Angara River

In petroleum refining, the problem of protecting the environment is solved in two directions: reducing refinery emissions into the atmosphere and discharge of wastewaters into bodies of water; improving the quality of the petroleum products to increase their environmental safety. Translated fromKhimiya i Tekhnologiya Topliv i Masel, No. 3, pp. 47 – 48, May – June, 2000.     

Formation of Metastable Aluminides in Alloys of Al – Hf – Sc (Ti) Systems

Metal Science and Heat Treatment - The methods of optical and scanning electron microscopy and x-ray spectrum microanalysis are used to study and to compare the special features of formation of...     

Effect of Temperature on the Formation of Stable and Metastable Aluminide Phases in Al‒Zr‒Nb Alloys

Russian Journal of Non-Ferrous Metals - The conditions of the formation of stable and metastable aluminides Aln(Zr1 – xNbx) formed during the crystallization of superheated...     

Electrode gauge as an instrument for studying shock compression and metallization of the substance

An electrode gauge for particle velocity is used to study condensed substances that acquire high electrical conductivity under shock compression. Thin metallic electrodes are placed into the substance. A shock wave propagates over the substance along the electrodes in a transverse magnetic field. A moving conducting substance closes the electrodes and generates an electromotive force on them. To justify the operation principle of the electrode gauge, the electrical conductivity of selenium and aluminum powders is measured. The high electrical conductivity of the powders (up to ≈10⁴ Ω⁻¹ · cm⁻¹) allows the electrode gauge to be used for determining the kinematic characteristics of the shock wave. The voltage on the electrodes is proportional to the mean value of particle velocity in the probing conducting layer located directly behind the shock front. Introduction of additional electrodes into the measurement cell allows the wave velocity to be found. This technique is used to plot the shock adiabats of selenium and aluminum powders of different densities. The experimental data obtained are presented as linear dependences of wave velocity on particle velocity. For a powder with large particles, the thickness of the probing layer is commensurable with the shock-transition width. This offers a possibility of using the electrode gauge to study the structure of the shock transition and the phase of substance metallization. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 5, pp. 116–125, September–October, 2007.     

Phase transformations in shock-compressed ytterbium

In order to study the phase transformations of ytterbium under shock compression, the electrical resistance of ytterbium at the initial temperatures of 77 and 290 K and a shock pressure of p ? 20 GPa is measured. The dependence of ytterbium resistance on pressure is nonmonotonic and indicates three successive phase transitions. At p ≈ 2 GPa, ytterbium enters a state with a high electrical resistance of the semiconductor type. The ytterbium bandgap at p ≈ 1.8 GPa is estimated as ≈0.02 eV. At p ≈ 3 GPa, the electrical resistance of ytterbium decreases due to a polymorphic phase transition The electrical resistance grows with further increase in pressure, and at p > 11 GPa, it does not change. The nature of the third transition is determined by calculating the temperature of the sample under shock compression. Analysis of the dependence of sample temperature on shock pressure, together with the phase diagram of ytterbium, suggests that the third transition is caused by ytterbium melting.     

Preparation and Heat Resistance of Porous Titanium Carbosilicide

Refractories and Industrial Ceramics - The results of studies on the preparation of titanium carbosilicide with porosities of 20, 40, and 60% are presented. Experimental samples were obtained using...     

A capacitive storage for a tabletop X-ray laser for dense-plasma diagnostics

The results of investigation of a pulsed capacitive energy storage for a tabletop-type X-ray laser for dense-plasma (up to 3 × 10²² cm^?3) diagnostics are presented. It is assumed that plasma of Ne-like argon is the active medium of the X-ray laser and an electric discharge occurs inside a 150-mm-long ceramic capillary 3–4 mm in diameter. In previous experiments on the SIGNAL accelerator, the main initial conditions for generation of laser X rays were determined and X rays at a wavelength of 46.9 nm were obtained. The pulsed capacitive-energy storage unit is built in the form of a flat capacitor filled with deionized water. It has been revealed that deionized water as the dielectric filling the flat capacitor is not broken down in a 10-mm-wide gap at a pulsed voltage <130 kV and a charging-pulse duration of ～300 ns. In this case, the parameters of the pulsed capacitive-energy storage correspond to those required for generation of laser X rays: a current amplitude in the load of 50 ± 1 kA and a period of the current in the load of 196 ± 2 ns. The small jitter of the duration of the charging pulse (288 ± 6 ns) of the flat capacitor offers a hope for satisfactory synchronization of a laser X-ray pulse with a diagnosed plasma object.