Dynamic polarizability and the theory of the ion-acoustic turbulence in a plasma containing ions of two species

A damping rate of the induced scattering of fast ion-acoustic waves on ions, the explicit form of which depends on the plasma polarizability at the frequency of beats of the interacting waves, was determined for a nonisothermal plasma containing hot electrons and cold ions of two species. In the case of a plasma containing mobile light ions and slow heavy ions, a new phenomenon of significant decrease in the probability of induced scattering was established. This effect is related to the fact that a contribution to the dielectric function of slow ions, determining the scattering amplitude, depends on both spatial and frequency dispersion. It is shown that this decrease in the induced scattering probability leads to a growth of the turbulent noise level and to a change of the anomalous transport coefficients in the limit of large turbulent Knudsen numbers. The same effect is responsible for a relative decrease in the runaway electron production.     

Interaction of ion-acoustic solitons with Langmuir turbulence

The interaction of ion-acoustic solitons with Langmuir waves has been considered. Investigation was performed in the approximation of a slow change in soliton parameters compared with the time of evolution of wave spectrum. This permitted a two-stage solution of the problem. First the Langmuir wave spectrum changes in the given field of a soliton were found. Then the action of high-frequency waves on the soliton was taken into account.     

On ion beam-plasma wave modes and ion beam deceleration by ion-acoustic turbulence

The properties of ion beam-plasma wave modes have been utilized to diagnose the ion beam deceleration by ion-acoustic turbulence in a multidipole plasma device.     

Stimulated Brillouin scattering in a plasma with ion-acoustic turbulence

A theory of stimulated Brillouin scattering (STBS) in a plasma with ion-acoustic turbulence is developed using concepts of parametric instability under conditions when equations of two-temperature hydrodynamics can be used to describe ion-acoustic perturbations of the electron density. The temporal growth rate of the absolute instability and the spatial gain of the scattered wave are determined. The dependence of the threshold density of the radiation flux on the angle between the scattering wave vector and the direction of anisotropy of the turbulent noise is described. A new effect of STBS forbiddenness caused by anomalous turbulent heating of the ions is predicted for a plasma with a high level of turbulent noise.     

Recalculation of the diffusion tensor for plasmas with ion-acoustic turbulence

The quasi-linear theory of a plasma with wave-particle collisions is reconsidered for the case of current-driven ion-acoustic turbulence. Especially the angular dependence of the energy spectrum of the waves is taken into account more accurately in the quasi-linear collision integral. The kinetic equation is solved assuming that the scales of the density gradients of the plasma parallel and perpendicular to an external magnetic field are much larger than the effective mean free path of the electrons. Expressions for the electron diffusion tensor are developed and estimates of the diffusion in solar flare plasmas are made.Published from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 39, No. 2, pp. 148–162, February, 1996.     

Collision integral for ions in plasma with ion-acoustic turbulence

For plasma with strongly developed ion-acoustic turbulence, an explicit expression for the ion collision integral was derived in the Bychenkov-Silin-Uryupin model [1].     

Amplification of ion-acoustic turbulence upon electron-cyclotron heating of plasma

In this paper, we present the results of the study of ion-acoustic turbulence upon electron-cyclotron heating of low-temperature plasma in a TAU-1 model setup. Two MI-167 magnetrons were used as microwave sources. The peak power of each magnetron was 1 kW, the pulse duration was 7.5 μs. An increase in the temperature of most electrons and an increase in the energy of nonthermal electrons were observed in experiments. Microwave field turning-on caused an increase by an order of magnitude in the spectral density of ion-acoustic noise in the entire frequency range from 0.3 to 3 MHz under study.     

Structure of ion-acoustic oscillation spectrum in high-current discharge plasma

The approximate dispersion laws for the normal modes of LF ion-acoustic oscillations in a cylindrical positive column are found. The oscillation spectra and correlation functions of high-current discharge ionic spontaneous emission are measured as a function of the plasma parameters and the tube length and diameter. They confirm the ion-acoustic nature of the oscillations. The mode structure of the spectra caused by a radial nonuniformity of the ion-laser plasma is detected for the first time.     

On the simple-source theory of sound from statistical turbulence

A theory for the generation of aerodynamic sound, stated in terms of convected simple sources and dipoles, is presented. The sources are found to depend upon convective derivatives of the hydrodynamic pressure within the turbulent source region. The results are similar to earlier efforts involving simple sources, sometimes called dilatational sources. The results are modified for effects involving measurements on moving flows. The theory shows explicitly the refractive effects of shear flow within the source region, as well as of temperature changes (if any) within the source region. The oscillating cylinder problem is discussed and the results of the present theory are found to agree with those obtained by Lauvstad using a matched asymptotic expansion for the same problem. The theory is used to predict the temperature dependence of sound power for hot jets.Consultant for Bolt Beranek and Newman, Inc.     

Numerical simulation of ion-acoustic turbulence in the B. B. Kadomtsev model

The present report is devoted to the discussion of the properties of two equations relatively long ago proposed by B. B. Kadomtsev for the nonlinear theory of ion-acoustic plasma turbulence and some results of their solutions. We concern with these equations as objects of mathematical physics, focusing attention to both the approach to their study and arising numerical results.     

On the critical regimes in the theory of randomly forced magnetohydrodynamic turbulence

In this paper large-scale properties of developed magnetohydrodynamic turbulence have been investigated by using double expansion method in the frame of quantum field renormalization group. It has been shown that universal kinetic scaling regime exists, but the double expansion in general leads to qualitatively different results than those provided by the usual -expansion treatment.This work was supported by Slovak Grant Agency for Science.     

On the interpretation of anticommuting variables in the theory of superspace

On the basis of cohomology theory, we consider a possible topological interpretation of Grassmann algebra used in the definition of superspace.     

Pressure spectrum in homogeneous turbulence

The pressure spectrum in homogeneous steady turbulence is studied using direct numerical simulation with resolution up to 1024(3) and the Reynolds number R(lambda) between 38 and 478. The energy spectrum is found to have a finite inertial range with the Kolmogorov constant K = 1.65+/-0.05 followed by a bump at large wave numbers. The pressure spectrum in the inertial range is found to be approximately P(k) = B(p)epsilon;(4/3)k(-7/3) with B(p) = 8.0+/-0.5, and followed by a bump of nearly k(-5/3) at higher wave numbers. Universality and a new scaling of the pressure spectrum are discussed.     

Kinetic equations for ions in plasma with ion-acoustic turbulence in the case of two ion types

Explicit expressions for ion kinetic equations were derived considering ion-acoustic turbulence of plasma, when the presence of two ion types enhances stimulated scattering of ionacoustic waves on ions.     

On the theory of turbulence: A non eulerian renormalized expansion

A non Eulerian framework for a renormalized theory of isotropic homogeneous steady state turbulence at high Reynold's numbers is developed. By construction it is invariant under random Galilei transformations. A direct interaction factorization is free of infrared singularities and yields Kolmogorov scaling for the static as well as for the dynamic correlation and response functions.