The influence of excited levels on the circumstellar gas ionization rate

It is shown that the gas surrounding a hot star is excited mainly by the stellar radiation field. The contribution of the excited states to the ionization rate R _exc can noticeably exceed that of the basic state R _base. A simple approximation formula is obtained for the ratio R _exc/R _base.     

Speedup of doping fronts in organic semiconductors through plasma instability

The dynamics of doping transformation fronts in organic semiconductor plasma is studied for application in light-emitting electrochemical cells. We show that new fundamental effects of the plasma dynamics can significantly improve the device performance. We obtain an electrodynamic instability, which distorts the doping fronts and increases the transformation rate considerably. We explain the physical mechanism of the instability, develop theory, provide experimental evidence, perform numerical simulations, and demonstrate how the instability strength may be amplified technologically. The electrodynamic plasma instability obtained also shows interesting similarity to the hydrodynamic Darrieus-Landau instability in combustion, laser ablation, and astrophysics.     

High-Precision Studies of the Compressibility and Relaxation of g-As2S3 Glasses at High Hydrostatic Pressures up to 8.6 GPa

Journal of Experimental and Theoretical Physics - The high-precision volume measurements of the g-As2S3 glass have been performed at high hydrostatic pressures up to 8.6 GPa, and room temperature....     

Electromagnetic waves reflected from the plate of a magnetic with a ferromagnetic spiral

The spectrum of coupled spin and electromagnetic waves is obtained for a magnetic with a ferromagnetic spiral structure determined by nonuniform exchange and relativistic interactions. It is shown that resonant interaction between spin and electromagnetic waves is possible. The electromagnetic wave reflectance from the plate of a magnetic with a ferromagnetic spiral is calculated for different spiral angles.     

Propagation of a Surface Magnetoelastic Wave in a Ferromagnet Near the Orientation Phase Transition

Physics of the Solid State - The frequency dependences of the group velocity and the damping of a magnetoelastic surface wave have been studied at various values of an external magnetic field and...     

Base Drag Reduction and Generation of the Lifting Force Using a Microwave Discharge in a Supersonic Flow

Technical Physics - We report on the results of experimental investigation of forced action of a deeply subcritical microwave discharge initiated in a quasi-optical electromagnetic beam on bodies...     

Prediction of higher heating values of plant biomass from ultimate analysis data

For natural plant raw materials and for artificial mixture samples with different lignin content, a comparison between empirical equations for the calculation of higher heating values was carried out relying on the data of ultimate analysis. Selection of tested equations from already known was carried out according to the criteria: equations should be intended for work with plant raw materials; the range of used materials should be rather wide; the data on element content (C, H, N, S) obtained experimentally and in routine mode, as well as ash value of the material, should be variables; ambiguous equations should be excluded. Only 8 from more than 150 published equations were chosen for testing, and 3 of these provide calculation of higher heating values with a less than 5–6% deviation from reference values obtained by means of combustion in an adiabatic calorimeter.     

Ionization of an air-methane mixture in a near-critical electric field

The process of effective ionization at the early stages of development of an electric discharge in methane-air mixtures at moderate and high pressures is analyzed. The ionization in an external electric field with consideration given to background electrons, electron attachment to and detachment from atoms and oxygen molecule, recharging, and anion-neutral electron exchange is considered. The dependences of the rates of ion-molecular processes on the temperature and electric field strength are examined.     

Towards a predictive scenario of a burning accident in a mining passage

To reveal the inner mechanisms of a combustion accident in a coalmine, the key stages and characteristics of premixed flame front evolution such as the flame shapes, propagation speeds, acceleration rates, run-up distances and flame-generated velocity profiles are scrutinised. The theories of globally spherical, expanding flames and of finger-flame acceleration are combined into a general analytical formulation. Two-dimensional and cylindrical mining passages are studied, with noticeably stronger acceleration found in the cylindrical geometry. The entire acceleration scenario may promote the total burning rate by up to two orders of magnitude, to a near-sonic value. Starting with gaseous combustion, the analysis is subsequently extended to gaseous-dusty environments. Specifically, combustible dust (e.g. coal), inert dust (e.g. sand), and their combination are considered, and the influence of the size and concentration of the dust particles is quantified. In particular, small particles influence flame propagation more than large ones, and flame acceleration increases with the concentration of a combustible dust, until the concentration attains a certain limit.     

Detachment of electrons from atmospheric oxygen molecules in a high electric field

The results of experiments on the electrical breakdown of air in a quasi-optical microwave beam with a deeply subcritical initial field have been reported. Breakdown has been initiated by a cylindrical vibrator with spherically rounded ends and a vibrator with a tapered end. The experimental data suggest that the amount of initial breakdown-initiating electrons in a breakdown area can be provided by the detachment of electrons from atmospheric oxygen molecules. The effect of detachment depends on the field strength.