Andrei N. Starostin

Quantum corrections to the distribution function of particles over momentum in dense media

A simple derivation of the Galitskii–Yakimets distribution function over momentum is presented. For dense plasmas it contains the law ∼p−8 as a quantum correction to the classical Maxwellian distribution function at large momenta. The integral equation for the width of the spectral distribution of kinetic Green functions is analyzed. The asymptotic behavior of the quantum corrections to the distribution function of particles is expressed via the Fourier transform of the wave function in the external potential. It is shown that the asymptotic power law for the distribution function over momentum is also correct for a non-equilibrium at the external electrical and laser fields.

Influence of quantum effects on the initiation of ignition and detonation

A theoretical analysis that allows one to quantify the quantum corrections to the rate constants of endothermic reactions associated with an increase in the high-energy tails of the momentum distribution functions at high pressures due to a manifestation of the uncertainty principle for the energy of the colliding particles at a high collision frequency is performed. The initiation of ignition of hydrogen-oxygen mixtures is investigated and special series of experiments on the initiation of detonation waves of condensation in carbon suboxide and acetylene at elevated pressures near the low-temperature limits have been carried out. The experimentally observed deviations in the Arrhenius dependences of the induction periods of the initiation of hydrogen ignition and detonation waves of condensation are shown to be well described by the proposed quantum corrections.

Electron distribution function and rate coefficients in a nonideal plasma in a strong laser field

The generalized distribution of electrons in energy and momentum is calculated in a nonideal plasma in a strong laser field. It is shown that the non-equilibrium generalized distribution leads to the power tails in the electron momentum distribution and a steep exponential rise in the rates for electron threshold processes. Taking into account the Pauli blocking shows a drastic rise in the rates in a strong laser field (for non-equilibrium distribution). An equation for the energy and momentum-dependent collisional width is derived in the Lorentz approximation. The numerical solution of this equation is used to calculate the momentum distribution function.

Experimental study of thermal radiation in dense sodium vapor for broad visible and infrared range

Purely thermal glowing of dense nonuniformly heated up to temperatures of 600–1200 K resonance medium (sodium vapor) in broad visible and IR spectral regions was investigated for the first time. Shape of obtained spectra and glowing absolute intensities in various spectral regions agree well with the numerical calculation results on the basis of the generalized theory of resonance radiation transfer.

Development of the theory of momentum distribution of particles with regard to quantum phenomena

A generalization of the theory of quantum asymptotics for the particle distribution function for large values of momentum is given that takes into account the energy exchange between a particle and an impurity. It is shown that, compared with the known power-law asymptotics, an additional exponential dependence on the kinetic energy arises with effective temperature higher than the temperature of the medium by a factor of the ratio of the impurity mass to the particle mass for a quantum correction to the Maxwell distribution function. New formulas are obtained for the rates of thermonuclear and threshold chemical reactions, that allow one to get rid of the inconsistencies of the previous theory when comparing with experiment.

Laser beam propagation in a turbulent atmosphere taking into account fluctuation of impurity concentrations

Propagation of laser beam in a turbulent atmosphere, at which are present resonance absorbing impurities, is featured by the parabolic equation of a quasi-optics. The spatial distribution of an impurity is nonuniform, fluctuation of its concentration, as well as fluctuation of density of a pure atmosphere, influences on structural function of an inductivity fluctuations. The analysis of propagation of laser beams will be carried out with the help of the equation for the moments of amplitudes of a field obtained from the parabolic equation with a random function by an inductivity of medium with allowance for of influence of impurities.

Stimulated Raman scattering subject to nonlinear effects

A model is developed for the description of stimulated Raman scattering. This model allows for changes in the level populations due to radiative transitions and it can be used also for an arbitrary detuning of the pump radiation from the center of a line of an atom in the active medium. A study is made of the conversion of wide-band laser radiation into a Stokes signal. It is shown that this conversion is quite efficient and the Stokes signal gain corresponds to coherent scattering. This result is related to the matching of the phases of the pump and Stokes signals. Numerical investigations carried out using this model under the experimental conditions described elsewhere give results in agreement with the experimental data.

Experimental and theoretical investigation of a pulsed laser utilizing the CF4 molecule

An experimental investigation was made of the characteristics of a pulsed CF4 laser at high pump power densities. A radiation intensity of 0.5 MW/cm2 was obtained at a frequency of 615 cm−1 when the pump power conversion efficiency was 12%. Calculations are made of the laser parameters using steady-state and complete models. It is found that two-photon processes may play a decisive role in the lasing mechanism. The feasibility of using amplifiers to improve the radiation power in the 16μ range is determined.