The electron temperature in the plasma of a DC discharge created in a supersonic airflow

The plasma parameters of a pulsating DC discharge created in a supersonic airflow with a Mach number of M = 2 are determined. It is revealed that along with the intense bands of CN and the molecular nitrogen ion, as well as the spectral lines of atomic oxygen, nitrogen, hydrogen and copper, an intense continuous spectrum is observed in the spectrum of the gas-discharge plasma radiation, which is caused by the deceleration of electrons on ions. The dependences of the electron temperature on the discharge current and longitudinal coordinates are determined. It was revealed that the studied plasma is nonequilibrium, with the electron temperature being much higher than the gas temperature.     

Nonlinear dynamics of deformation bands in aluminum–magnesium alloy in the creep test

Various types of plastic instabilities that emerge in intermittent creep have been studied experimentally for AlMg6 aluminum–magnesium alloy. It has been shown that intermittent creep exhibits threshold dynamics. The deformation step on the creep curve of amplitude is ~1–6% and begins when the rate of the preceding continuous creep attains a certain critical value. In the course of evolution of the step, the strain rate varies in the interval that spans more than two orders of magnitude, and transitions occur between different dynamic regimes of type A and B characterized by different stress drop regularity levels in the force response. Nonlinear aspects of the deformation behavior of the alloy in the intermittent creep conditions are considered.     

Electron kinetics in a discharge plasma produced by a focused microwave beam in free space

A study is made of the electron kinetics in a discharge plasma produced by a high-power beam of electromagnetic radiation in the centimeter-wave region under conditions approaching free space, when the dimensions of the chamber are much greater than the wavelength of the microwave radiation. Two regimes of discharge production are investigated: the regime of short microsecond pulses at a repetition rate of 200 Hz, and a single millisecond pulse regime. It is shown that at threshold values of the microwave energy flux density the electron density in the initial stages of discharge formation reaches the critical value, and that the average energy of the electrons is of the order of 1.5–3 eV. Zh. Tekh. Fiz. 67, 10–14 (June 1997)     

Dynamics of deformation bands and fracture of the aluminum-magnesium alloy 5556

The dynamics of deformation bands at the prefracture stage of the aluminum-magnesium alloy 5556 has been examined using the high-speed video recording. It has been revealed that, in the artificially aged and recrystallized alloys, the correlations between the propagating deformation bands and the development of the main crack are of different character.     

Plastic deformation macrolocalization during serrated creep of an aluminum-magnesium Al-6 wt % Mg alloy

The nonlinear dynamics of the space-time structure of macrolocalized deformation is studied by a set of high-speed in situ methods under the conditions of serrated creep in an aluminum-magnesium Al-6 wt % Mg alloy at room temperature. Macroscopic deformation jumps with an amplitude of several percent are detected in the creep curve of this alloy. It is found that a complex space-time structure of macrolocalized deformation bands moving in a correlated manner forms spontaneously in the material during the development of a deformation jump. The difference between the observed picture of deformation bands and the well-known Portevin-Le Chatelier classification of deformation bands is discussed.     

Analysis of non-linear ion drift in spectrometers of ion mobility increment with cylindrical drift chamber

A model for the drift of ions under a non-uniform, high-frequency electric field in the drift chamber of a spectrometer of ion mobility increment is developed. For the general dependence of the ion mobility on the electric field strength and the general time-dependence of the separating voltage, we suggest a procedure for calculating of the ion peak form. The shape of the peak for the ion focusing and defocusing conditions has been obtained.     

Electrochemical Emission during the Straining and Destruction of an Aluminum–Magnesium Alloy in an Aqueous Medium

Technical Physics - The spatiotemporal structures of Portevin–Le Chatelier deformation bands at the stage of neck formation and fracture of an aluminum–magnesium alloy deformed in an...