Tandem Accelerator with Vacuum Insulation for Boron-Neutron-Capture Therapy and Detection of Explosives by Resonance Absorption of γ-Rays

The status of the design work on an electrostatic tandem-accelerator with vacuum insulation for 2.5 MeV protons and up to 40 mA constant current is reported. This machine is to be used for solving problems of neutron therapy and the detection of explosives by nuclear-resonance absorption of -rays.     

Induction period of a two-component aerosol of liquid oxidizer and propellant

The problem of self-ignition of a two-component aerosol consisting of uniformly mixed drops of an oxidizer and a propellant reacting in the gas phase is considered. The process of self-ignition of such an aerosol is divided into two stages: vaporization of aerosol components and subsequent chemical heating of the mixture. An approximate analytical formula is derived, for the period of self-ignition of a two-component aerosol. This formula takes into account the differences in thermophysical characteristics of aerosol liquids, mass concentrations, sizes of the drops of aerosol components, and the difference between the initial temperature of these drops and the initial temperature of the gas phase. The calculation results for the self-ignition period obtained using this analytical formula and the results of numerical solution of the problem in the zero-dimensional formulation coincide within 20% in a wide range of the governing parameters of the problem. Translated fromFizika Goreniya i Vzryva, Vol. 35, No. 6, pp. 15–21, November–December 1999.     

Self-ignition of a two-component gas suspension

The self-ignition of a motionless cloud of particles of two sorts (the two-component gas suspension) is studied. We obtain approximate analytical expressions for the induction period and critical conditions of self-ignition in the case where the heat exchange occurs between the cloud and the ambient medium and in the case where one of the components consists of the particles of a substance that is reactive in the endothermic chemical reaction. These formulas are compared with the numerical solution of the unsteady problem, and their domains of applicability are found. Translated fromFizika Goreniya i Vzryva, Vol. 35, No. 5, pp. 6–13, September–October 1999.     

Modeling of flame propagation in a mixture of combustible gases and particles

A physicomathematical model of flame propagation over a gas suspension composed of a mixture of gases (oxidizing, combustible, and inert components) and the particles of a condensed material that reacts heterogeneously with the oxidizing component is formulated. Numerical simulations are used to obtain a dependence of the flame velocity on the parameters related to the mass concentration of the particles, the particle size, the activation energy of a heterogeneous reaction on the particle surface, the heat of the heterogeneous reaction, and the mass exchange of the particles. Depending on the ratio of the dispersed-phase parameters, the flame velocity in this medium can increase severalfold in comparison with the flame velocity in a dust-free gas mixture or decrease. In the latter case, the effect of the particles is similar to the effect of the inert dispersed phase. Translated fromFizika Goreniya i Vzryva, Vol. 36, No. 2, pp. 3–9, March–April, 2000.     

Nonsteady-state interaction of a combustion wave with a dust cloud

A mathematical model of inhibition of gas flames by inert powders is studied.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 55, No. 2, pp. 236–243, August, 1988.