Concentration of $H^-$ in the positive column of low-pressure hydrogen plasma
Concentration of $H^-$ in the positive column of low-pressure hydrogen plasma
A.M. Devyatov, A.V. Kalinin, Li Soong Chang, S.R. Mijovic
Concentration of negative ions in the positive column of the low-pressure hydrogen plasma was calculated. The main processes of formation and loss of negative ions were taken into account in the calculations. The effective coefficient of diffusion of $H^-$ ions in hydrogen was determined. The upper limit of the $H^-$ ion concentration was estimated experimentally.
Show AbstractProbe diagnostics of plasma containing negative iodine ions
Probe diagnostics of plasma containing negative iodine ions
L.M. Volkova, A.M. Devyatov, S.R. Mijovic, M.K. Tarakji
The temperature, the electron energy distribution function (EEDF), and the concentrations of electrons and iodine ions (positive and negative) were determined for a mixture of helium with iodine vapors by treatment of the current voltage characteristics of a single cylindrical probe and by the method of the probe current second derivative. The results obtained from solving balance equations are in fair agreement with the measurement data.
Show AbstractErgodicity problem for multimode signals
Ergodicity problem for multimode signals
A.G. Vologdin, V.D. Gusev
Broad possibilities are demonstrated for the investigation of ergodicity of stationary random processes using characteristic functions. A stochastic interference signal model is considered that is stationary for any number of constituent modes. Its ergodicity relative to the characteristic function, probability density, and moments is proved for the number of modes $m$ = 1, 2. The question of practical application of the results for a finite averaging time is discussed.
Show AbstractHermitian quadratic form for the transmission coefficient of a paraxial wave
Hermitian quadratic form for the transmission coefficient of a paraxial wave
Yu.K. Alekseev, A.I. Kostienko, S.A. Krut'kova
An approximate theory of propagation of a Gaussian-Hermitian bounded wave beam obliquely incident on an arbitrary plane-conserving electrodynamic structure was constructed using the Rayleigh formalism in the paraxial approximation. The transmission coefficient of the structure is represented as a rapidly converging quadratic Hermitian form comprising the relevant plane-wave factors and their spatial derivatives. The form obtained is convenient for both a numerical study of reflection, absorption, and propagation of bounded wave beams in various media and for analytic calculations and estimations.
Show AbstractOn the possibility of strong compression of pulsed signal in a linear medium with arbitrary dispersion characteristic
On the possibility of strong compression of pulsed signal in a linear medium with arbitrary dispersion characteristic
Yu.E. Dyakov
A general method is proposed for obtaining strong compression of pulses with any form of dependence of the wave number $k(\omega )$ on the frequency $\omega$. Compression of a super-Gaussian pulse in a medium with n-th order dispersion is discussed in detail.
Show AbstractDetermination of lasing-level populations in a longwave $Q$-switched $СО_2$-gasdynamic laser
Determination of lasing-level populations in a longwave $Q$-switched $СО_2$-gasdynamic laser
A.N. Baranov, O.I. Ivanova, A.I. Odintsov, A.I. Fedoseev
The feasibility has been shown of diagnostics of vibrational-level populations in the active medium of a coupled-mode $СО_2$-gasdynamic laser using the energy characteristics of pulsed operation in a Q-switched regime. The expressions have been derived for the determination of the initial population difference of lasing levels from the data measured. Experiments were performed on the $03^10—10^00$ ($\lambda$ = 18.4 μm) and $04^20—03^30$ ($\lambda$ = 17.2 μm) transitions in a $СO_2 —Аr$ gas mixture. An advantage of the method consists in that the use of the $Q$-switched regime allows one to exclude the interaction of vibrational transitions during lasing.
Show AbstractLight and dark nonpropagating solitons on liquid surface
Light and dark nonpropagating solitons on liquid surface
A.V. Vederko, V.F. Marchenko, A.P. Sukhorukov
Localized nonpropagating perturbations of the surface which have a soliton shape and arise from vertical oscillations of a cell with a liquid, have been studied theoretically and experimentally. It has been found that both light and dark nonpropagating solitons can be produced depending on the liquid depth, i. e., on the sign of cubic nonlinearity of the medium.
Show AbstractThermo emf in amorphous ferromagnetic alloys
Thermo emf in amorphous ferromagnetic alloys
A.D. Arsenyeva, A.V. Vedyaev, R.P. Vasilyeva, A.B. Granovskii, G.M. Myalikgulyev, A.V. Pechennikov, A.F. Prokoshin, S.M. Stadnik
The theory of the thermo emf of amorphous ferromagnetic materials has been extended to the case of $d$-like current carriers. The thermo emf of Fe-Ni-Si-B and Fe-Co-Cr-Si-B alloys has been measured in a wide temperature range. An extremum in the thermo emf vs temperature curve characteristic of amorphous ferromagnetic materials becomes more pronounced after crystallization. This feature is due to the prevailing contribution of inelastic scattering during crystallization.
Show AbstractFerrimagnetic spin glass with fluctuating anisotropy
Ferrimagnetic spin glass with fluctuating anisotropy
Bach Than' Kon, A.V. Vedyaev
The effect of fluctuating one-ion anisotropy on the temperature of transition from a paramagnetic state to a spin glass state is discussed within the framework of the two-sublattice model with the infinite interaction radius. It is shown that the proposed theory makes it possible to explain the available experimental data for some substituted ferrimagnetic spin glasses.
Show AbstractVariational theory of nematic liquid crystal
Variational theory of nematic liquid crystal
I.P. Bazarov, E.V. Gevorkyan, V.M. Polyakov
A model of a nematic liquid crystal which takes into account orientational fluctuations and short-range correlations of molecules has been studied based on Bogolyubov's variational principle in a pseudoharmonic approximation. The temperature dependences of the mean-square orientational displacement of molecules and the order parameter have been obtained.
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