Damping Of Plasma Oscillations Research Articles

Plasma vortices in the ionosphere and atmosphere

Vortices observed in ionized clouds of thunderstorm fronts have the nature of plasma vortices. In this work, the need to account for the electrostatic instability of plasma in the origination, intensification, and decay of plasma vortices in the atmosphere is shown. Moisture condensation results in mass-energy transfer under the inhomogeneous spatial distribution of aerosols. If a phase volume of natural oscillations is transformed in the frequency-wave vector space in inhomogeneous plasma, the damping of plasma oscillations promotes an increase in the pressure gradients normal to the geomagnetic field. Excitation of the gradient instabilities is probable in atmospheric plasma formations.

Saturation of two-stream instability of an electron beam in plasma

The development and nonlinear saturation of two-stream instability of a warm nonrelativistic electron beam in a cold plasma are investigated numerically in the framework of a one-dimensional model. It is shown that, for a sufficiently large velocity spread of the electron beam, instability develops and saturates according to a universal law, the wave phase velocity remains the same in the saturation stage, and the maximum field is somewhat lower than that predicted by classical estimates and depends in a different way on the growth rate. The damping of plasma oscillations not only changes the instability growth rate, but also substantially decreases the maximum wave field.

Kinetic Eigenmodes and Discrete Spectrum of Plasma Oscillations in a Weakly Collisional Plasma

The damping of plasma oscillations in a weakly collisional plasma is revisited using a Fokker-Planck collision operator. It is shown that the Case--Van Kampen continuous spectrum is eliminated in the limit of zero collision frequency and replaced by a discrete spectrum. The Landau-damped solutions are recovered in this limit, but as true eigenmodes of the weakly collisional system. For small but nonzero collision frequency, the spectra and eigenmodes are qualitatively different from their counterparts in the collisionless theory. These results are consistent with recent experimental findings.

Spectrum of plasma oscillations in structures with a periodically inhomogeneous two-dimensional electron plasma

We develop a rigorous electrodynamic theory of plasma oscillations in a periodically inhomogeneous two-dimensional electron system with a rectangular profile of the spatial modulation of the equilibrium electron concentration. We calculate the frequencies and radiative damping of the main plasma-oscillation types with a zero reduced wave vector. We show that the frequency splitting and the radiative damping of the oscillations are nonmonotonic functions of the modulation percentage and the ratio of the widths of the bands of two-dimensional plasma with low and high electron concentrations. The results of calculations are compared with experimental data and with the results of a perturbation theory developed in earlier work of other researchers. We discuss the physical mechanism for the emergence of radiative damping of plasma oscillations.

Damping of plasma oscillations in hot gluon matter

The computation of the damping constant of QCD plasma oscillations is discussed in the physical Coulomb and temporal axial gauges in the framework of a consistent linear response analysis. To bare one-loop order the waves damp by decaying into two massless gluons, and the two gauges give the same result for the damping constant. It is pointed out that, due to the infrared behaviour of the theory, higher-order corrections will modify the result and an example showing how they may do this by turning the gluons effectively massive is given.

Exact damped sinusoidal electric field of nonlinear one-dimensional Vlasov-Maxwell equations

An exact solution for a temporally damped sinusoidal electric field which obeys the nonlinear, one-dimensional Vlasov-Maxwell equations is given. The electric field is a generalization of the O'Neil model electric field for Landau damping of plasma oscillations. The electric field is a special case of the form found from the invariance of the one-dimensional Vlasov equation under infinitesimal Lie group transformations. The time dependences of the damping decrement, of the wave-number and of the angular frequency are derived. Use of a time-dependent BGK one-particle distribution function is justified for weak damping where, in general, it is necessary to carry out a numerical calculation of the invariant of which the distribution function is a functional.

High-speed switching and logic circuits using Josephson devices

We have investigated the use of Josephson devices as switching components for computer circuits. One part of this work is a study of the switching properties of the superconductor-semiconductor-superconductor junction. The switching speeds of a single junction and a basic memory cell, computed by numerical methods, are comparable with the corresponding values for oxide-barrier junctions. Having a much lower Q than the conventional oxide-barrier junction, it should not have the previously experienced difficulties caused by junction resonances. The damping of plasma oscillations in the semiconductor junction is also more effective, leading to a shorter switching time. A new type of logic gate employing Josephson devices has been investigated. This circuit would automatically unlatch after each operation, thus requiring no external means for resetting. Numerical analysis predicts subnanosecond switch-reset operation for appropraite parameter choices. The qualitative behavior of the circuit has also been shown with a mechanical analog.

Energy Loss of Charged Particles in a Plasma

Formulas for the stopping power of a nonrelativistic ionized gas for electrons, protons, and other structureless charged particles are derived. The primary velocities considered extend from values comparable to those of the plasma electrons up to values in the relativistic range. New results are obtained for the lower primary velocities, in that full account is taken of the effect of the initial velocity distribution of the plasma electrons on binary collisions as well as on collective excitations. Formulas for the case of non-negligible damping of plasma oscillations are given and comparisons are made with the impact-parameter method and with particle kinetic theories.

Damping of Plasma Oscillations in Atoms

Using the Thomas-Fermi model of the atom, we calculate the damping of collective oscillations due to the excitation of bound electrons to free states. We find that in some cases the decay time is much longer than the period of the oscillation. Our results indicate that weakly damped plasma oscillations can exist in atoms.

The damping of plasma oscillations in a magnetic field

The damping of plasma oscillations in a magnetic field

Damping of Waves in Electron Beams

The damping of plasma oscillations in velocity-modulated electron beams with large-velocity spreads has been analyzed. It is shown that the observed spatial decay of rf current along the beam (a loss of the fundamental interference pattern) can be characterized by the exponential decay of one of the space-charge waves. The exponential-decay rates for this wave are extracted from the data of over 50 experiments which exhibited a spatial damping. The parameters of the measured ``near-Maxwellian'' distribution of velocities (cutoff with a slow ``tail'') associated with each decay lead to the characterization of an equivalent temperature for the beam condition of each experiment. This is used to calculate the damping-determining parameters (ratio of plasma wavenumber to Debye wavenumber, k/kD, or equivalent). The experimentally observed damping rates for a variety of beam conditions are found to vary with k/kD in a consistent fashion and are also comparable with rates extracted from electron-beam theories. This is interpreted as a demonstration of a damping mechanism without collisions, and leads to the ascription of the decay as Landau damping in electron beams. Further experiments, in which the decay is observed as a function of the driving amplitude of the electron-beam plasma oscillations, are studied as possible evidence of Landau damping in electron beams.

Interaction between Plasma Oscillation and Radiation Field I; Radiation Damping of Plasma Oscillation

The interaction mechanism between plasma oscillation and radiation field in high temperature plasma is discussed with quantum mechanical treatment in the absence of external magnetic field. The radiation damping of plasma oscillation is evaluated and compared with the Landau damping, mode-coupling damping and collision damping. The radiation damping is much larger than the Landau damping in the range of wave vector of plasma oscillation k < k D /7 and is smaller than the mode-coupling damping by the order ( v T / c ) 3 for all range of k , where k D is the Debye cut-off wave vector, v T is the mean thermal speed of electrons and c is the light velocity.

Collisional Damping of Plasma Oscillation

The coefficient of collisional damping of the electron plasma oscillation is calculated by means of Boltzmann's collision term in the limit of long wave length. The damping coefficient is given by \begin{aligned} \omega_{i}{=}\frac{1}{2}\varLambda_{00}^{(1)}+\frac{2}{3}(\varLambda_{00}^{(2)}+\lambda_{00}^{(2)})\left(\frac{k}{k_{D}}\right)^{2}, \end{aligned} where k D is the inverse of the Debye length and k is the wave number. The constants \(\varLambda_{00}^{(1)}\), \(\varLambda_{00}^{(2)}\) and λ 00 (2) are collision integrals. The first corresponds to the change of the momentum of the electrons due to collisions with the ions. The second and the third are equal to the rates of relaxation of the elliptic velocity distribution of the electrons due to electron-ion and electron-electron interactions, respectively.

General Expressions of Absorption Coefficient and Radiation Intensity in Plasma and Kirchhoff's Law

General expressions of absorption coefficient K(w) and radiation intensity J(w) in plasma are given from the discussions of the time variation in the number distribution function of incident photon, and in terms of these quantities Kirchhoff's law in plasma system is discussed. It is well known that this law represents a general relation which holds between K(w) and l(w), and that it does not depend on a particular process which results in the absorption or emission of photons, but only on the temperature. The formal aspects of this. fact are given from general expressions of K(w) and J(w). Furthermore, using the close parallel discussion to photon case, it is shown that Landau damping of plasma oscillation may be interpreted as a net damping of plasmon distribution function due to the direct interaction with electron.

Damping of Plasma Oscillations in the Linear Theory

The problem of stable oscillations of an infinite plasma is re-examined from the standpoint of an integral equation for the electric potential in the plasma. The behavior of a plasma with a Lorentz distribution is solved completely. We show how one may compute, under suitable restriction, the initial velocity distribution when the electric potential has been specified for all time. We then solve for an initial velocity distribution which yields an electric potential which is nonoscillatory in character and damps as a Gaussian distribution in time; the initial velocity distribution is proved to be an entire function in velocity space. Since this result is contrary to that of Landau, we re-examine his method of determining the electric potential.

On the Damping of Plasma Oscillations

On the Damping of Plasma Oscillations