Prospects for the use of diethynylbenzene as a fuel dispersant for rocket ramjet engines

Russian Chemical Bulletin - The applicability of 1,4-diethynylbenzene (DEB) as a dispersant of solid fuels was studied. The atmospheric flight ranges of an aircraft with a rocket ramjet engine...     

Calculation of Bound and Resonant Levels of Acceptors in Narrow-Gap CdHgTe Solid Solutions

JETP Letters - The wavefunctions of an electron in the field of a singly charged acceptor in narrow-gap CdHgTe solid solutions are calculated taking into account the central-cell potential. By...     

Formation of x-ray images by the action of an optical image on a diffracting lithium niobate crystal

A possible mechanism for the formation and processing of an x-ray image using a corresponding optical image as a template is considered. The method is based on the thermal influence of light on the x-ray diffraction parameters of an LiNbO₃ crystal. A mechanism for the influence of the gradients of the temperature fields formed in the crystal on the x-ray structural parameters of the crystal is proposed. Information which permits the evaluation of some practical aspects of the application of the observed effect in technology is given. Zh. Tekh. Fiz. 67, 76–79 (September 1997)     

Cyclotron resonance in HgTe/CdTe(013) narrowband heterostructures in quantized magnetic fields

Electron cyclotron resonance in HgTe/CdTe(013)-based narrowband heterostructures with a noninverted band structure in quantized magnetic fields has been investigated at different electron concentrations. Cyclotron transitions from the lower Landau levels of the conduction band have been discovered. The Landau levels have been calculated in the Kane model with the inclusion of strain. Comparison with the experimental data indicates that the energies of the observed cyclotron resonances are systematically higher than the calculated ones.     

Burning of Solid Propellant in Gas Generator of an Air-Breathing Engine at Large Content of Metal

Russian Journal of Applied Chemistry - The features of burning of solid propellant with a high metal content (over 40%) under conditions of a separately located gas generator of an air-jet engine...     

Polarization dependence of Fano resonances in impurity photoconductivity of quantum wells doped with shallow donors

The spectrum of impurity photoabsorption of a heterostructure with quantum wells doped with shallow donors has been calculated in the energy range close to the optical phonon energy. It has been shown that the resonant feature of photoconductivity (Fano resonance) caused by the interaction of electrons with polar optical phonons depends strongly on radiation polarization when the resonance state energy is higher than the energy of the bottom of the second quantum-well subband. This dependence on polarization has been experimentally revealed in the impurity photoconductivity spectrum of the AlGaAs/GaAs heterostructure.     

Filtration Combustion of Humid Fuels

A comparative study of the filtration combustion of two types of fuel in mixtures with an inert material at various degrees of humidity was performed. The fuels were activated birch charcoal and pinewood. It was demonstrated that the combustion of activated charcoal was only slightly affected by humidity. In the case of pinewood combustion, an increase in the fuel humidity caused substantial decreases in the gasification mass rate and temperature. The composition of the gaseous products was found to change only for mixtures containing a large amount of pinewood with a humidity of more than 35%. This can be accounted for by a change in the extent of pinewood pyrolysis.     

Kinetics of Thermal Decomposition of Solid Propellant Based on Aluminum and Ammonium Perchlorate

Kinetic regularities of the mass loss and heat and-gas release were studied in the thermal decomposition of a solid propellant composed of aluminum, ammonium perchlorate, and a polymer binder. It was shown that, under heating from 40 to 340°C under permanent vacuum conditions, propellant samples decompose without ignition, with the limiting mass loss in the decomposition being 48%. When experiments were performed in air, the propellant formulation decomposes with sharp ignition, with the inflammation temperature (270–287°C) and amount of volatiles released by this instant of time (10–16 wt %) dependent on the heating rate. The kinetic regularities of the mass loss in the decomposition of a solid propellant were described in terms of the polychromatic kinetics model that assumes that the reaction system has ensembles of particles differing in reactivity. The distribution functions of the mass fractions of the propellant by activation energies of decomposition were calculated. The heat release kinetics in the decomposition of a propellant formulation in the temperature range 153–270°C in a closed evacuated system is described by a sum of equations for two parallel reactions: 1st-order reaction with a heat effect Q₁ = 200 ± 5 kJ kg^–1 and 1st-order autocatalysis with heat effect Q₂ = 1900 ± 50 kJ kg–1. The rate constants and the activation parameters of the process were determined.

     

Filtration combustion of charcoal-polyethylene systems

The characteristics of the filtration combustion of a carbon-polyethylene-inert material mixture with superadiabatic heating are experimentally studied. It is demonstrated that the composition of the products and the nature of the thermal degradation of the polymer strongly influence the burning rate and thermal structure of the wave. In the filtration combustion wave, a part of the polymer can be pyrolyzed and carried away by the gas flow, with the rest of it being oxidized in the combustion zone.     

Photothermal Ionization Spectroscopy of Mercury Vacancies in HgCdTe Epitaxial Films

JETP Letters - The terahertz photoconductivity of narrow-gap Hg1 – xCdxTe alloys that originates from shallow double acceptors formed by mercury vacancies is investigated. The discrete...