Gauge covariant linear response analysis of QCD plasma oscillations

We show, using linear response theory, how plasma oscillations and screening in quark-gluon plasma can be computed in perturbation theory in a gauge covariant manner. Using this method we calculate the damping constant of color electric plasma oscillations in a Colomb gauge and show that the result agrees with an earlier calculation in the A₀ = 0 gauge.     

Spectrum of polariton excitations of a two-dimensional electron plasma in a magnetic field

Polariton excitations associated with magnetoplasma and cyclotron oscillations in a two-dimensional (2D) electron plasma are studied. In contrast to previous works by other authors, it is concluded that there exists a low-frequency nontransmission band in the spectrum of 2D surface magnetoplasma polaritons. Radiative polariton excitations associated with nonuniform cyclotron oscillations of electrons in a 2D system are investigated. Pis’ma Zh. éksp. Teor. Fiz. 68, No. 3, 200–204 (10 August 1998)     

Magnetotransport in a modulated two-dimensional electron gas

We propose a semiclassical theory of dc magnetotransport in a two-dimensional electron gas modulated along one direction with weak electrostatic modulations. We show that oscillations of the magnetoresistivity ρ_∥ corresponding to the current driven along the modulation lines observed at moderately low magnetic fields can be explained as commensurability oscillations.     

Radiative losses in plasma accelerators

We investigate the dynamics of a relativistic electron in a strongly nonlinear plasma wave in terms of classical mechanics by taking into account the action of the radiative reaction force. The two limiting cases are considered. In the first case where the energy of the accelerated electrons is low, the electron makes many betatron oscillations during the acceleration. In the second case where the energy of the accelerated electrons is high, the betatron oscillation period is longer than the electron residence time in the accelerating phase. We show that the force of radiative friction can severely limit the rate of electron acceleration in a plasma accelerator.     

Damping of longitudinal plasma oscillations

Attenuation of electron oscillations in a fully ionized plasma is investigated by solving linearized kinetic equation without external fields. The general dispersion relation for longitudinal plasma oscillations is obtained using the BGK model. Damping due to electron ion collisions is obtained with a correction term. It is also observed that damping rate decreases ask increases, which is in agreement with McBride.     

Dielectric response of a relativistic degenerate electron plasma in a strong magnetic field

The longitudinal dielectric response of a relativistic ultra-degenerate electron plasma in a strong magnetic field is obtained via a relativistic generalization of the Hartree self-consistent field method. Dispersion relations and damping conditions for plasma oscillations both parallel and perpendicular to the magnetic field are obtained. We also give detailed results for the zero-field case. Applications to white dwarf stars and pulsars are given.     

Magnetoresistance oscillations of two-dimensional electron systems in lateral superlattices with structured unit cells

Model calculations for commensurability oscillations of the low-field magnetoresistance of two-dimensional electron systems (2DES) in lateral superlattices, consisting of unit cells with an internal structure, are compared with recent experiments. The relevant harmonics of the effective modulation potential depend not only on the geometrical structure of the modulated unit cell, but also strongly on the nature of the modulation. While higher harmonics of an electrostatically generated surface modulation are exponentially damped at the position of the 2DES about 90 nm below the surface, no such damping appears for strain-induced modulation generated, e.g., by the deposition of stripes of calixarene resist on the surface before cooling down the sample.     

Surface plasma oscillations in silver films with navy surface profiles: A quantitative experimental study

The influence of a sinusoidal surface corrugation of a thin silver film on the damping and the phase velocity of surface plasma oscillations is determined quantitatively. The experimental results are compared with theoretical calculations on the basis of a theory developed by Kretschmann and Kröger.     

The plasma oscillations spectrum of a periodically inhomogeneous 2D electron system near the perforation threshold

The transformation of the spectrum of plasma oscillations with the zero reduced wave vector in the spatially modulated two-dimensional electron system moving to the regime of isolated quasi-one-dimensional electron channels is theoretically investigated. The results provide an explanation of the well-known experimental observations of the plasma resonance transformation when a two-dimensional electron system crosses the continuity violation threshold.     

Plasma oscillations in two-dimensional electron systems with a superstructure under Stark quantization conditions

The effect of quantizing electric field on plasma oscillations of two-dimensional electron gas in a system with a periodic potential has been theoretically investigated. The coupled-plasmon spectrum ω(q) is calculated for high temperatures (Δ ? T, where Δ is the conduction miniband width and T is temperature in energy units). The calculations are based on the quantum theory of plasma oscillations in the random-phase approximation, with allowance for the umklapp processes.     

Ion acoustic waves in the presence of electron plasma waves

Long-wavelength ion acoustic waves in the presence of propagating short-wavelength electron plasma waves are examined. The influence of the high frequency oscillations is to decrease the phase velocity and the damping distance of the ion wave.     

Experimental observation of nonlinear synchronization due to a single wave

A test electron beam is propagated in a specially designed traveling wave tube. It interacts with a nonresonant wave, and its energy distribution is recorded at the tube output. We report the direct experimental observation of the spatially periodic electron velocity bunching, and of a nonlinear effect on the electron velocity modulation: the synchronization of the particles with the wave responsible for Landau damping in plasma physics. The results are explained by second order perturbation theory in the wave amplitude.     

Electron oscillations in a plasma: Effect of collisions on Landau damping

Summary Electron oscillations in a plasma are analysed starting from the integral form of Boltzmann-Vlasov equation. The effects of collisions on Landau damping are shown. The conditions for Landau damping existence are derived.

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Riassunto Onde elettrostatiche in un plasma sono studiate ricorrendo alla forma integrale dell'equazione di Boltzmann-Vlasov. In particolare, sono stati evidenziati gli effetti prodotti sul Landau damping dalle collisioni. Si è ricavato che in certe condizioni le collisioni possono impedire il Landau damping e si sono ottenuti i valori di soglia.

     

Relativisitic longitudinal non-Abelian oscillations in quark-antiquark plasma

We study the relativistic version of the non-Abelian, longitudinal wave in quark-antiquark plasma reported earlier by Bhat et al [Phys. Rev. D39, 649 (1989)]. We have also relaxed various approximations they made in their analysis. Both the quark and antiquark dynamics are taken in our analysis. The non-linearity arising from non-Abelian field as well as from plasma are included. Hence it is an exact longitudinal mode in relativistic quark-antiquark plasma, relevant to the study of quark gluon plasma. We find that earlier results are reproduced for non-relativistic and low amplitude oscillations, but are modified for relativistic or large amplitude waves. Further more, the above results are based on just four first-order equations for gauge invariant quantities derived from gauge covariant twelve first-order equations.     

Coexistence of collective and single-particle effects in the photoresponse of a 2D electron gas to microwave radiation

The photoresponse of magnetoresistance of a high-density two-dimensional electron system to microwave electromagnetic radiation is studied. The damping of the Shubnikov-de Haas oscillation by radiation with a non-monotonic dependence of this effect on the magnetic field and the radiation-induced oscillations of magnetoresistance are observed. The damping is most pronounced within isolated narrow magnetic field intervals that closely correspond to the expected positions of magnetoplasma resonances in the sample under study and also near the cyclotron resonance position. A “window” is observed in the photoresponse near the field value predicted on the basis of a single-particle electron spectrum consisting of broadened Landau levels. The radiation-induced oscillations, the window in the photoresponse, and the damping of the Shubnikov-de Haas oscillations near the cyclotron resonance are described in terms of the theory based on the concept of the nonequilibrium filling of single-electron states. Thus, it is demonstrated that the photoresponse pattern observed in the experiment is formed by both single-particle and collective (magnetoplasma) effects.     

Colored plasmons in a quark-gluon plasma near equilibrium

Within a kinetic theory for QCD plasmas we study the color response function near thermodynamic equilibrium. Its poles yield a longitudinal and a transverse collective mode, both starting at the plasma frequency. Due to the gluon contribution there is no Landau damping for these modes, and creation of gluon or q-$\text{p}$ pairs is the dominant damping mechanism. In an electron plasma the generally quoted Landau damping near threshold is shown to be an artifact of the non-relativistic approximation.     

Measurement of Landau damping and the evolution to a BGK equilibrium

Linear Landau damping and nonlinear wave-particle trapping oscillations are observed with standing plasma waves in a trapped pure electron plasma. For low wave amplitudes, the measured linear damping rate agrees quantitatively with linear Landau damping theory. At larger amplitudes, the wave initially damps at the Landau rate, then regrows and oscillates, approaching a steady state, as predicted by O'Neil in 1965 [Phys. Fluids 8, 2255 (1965)]]. This BGK equilibrium is observed to decay slowly due to external dissipation.     

Oscillatory magnetoconductivity of a two-dimensional electron system due to phonon scattering

Summary A quantum-statistical theory of magnetophonon resonance oscillations in two-dimensional systems has been developed, starting from the resolvent representation of Kubo's formula and its proper connected diagram expansion. Non-polar and polar optical-phonon scattering has been considered and the results show, as anticipated based on the physical considerations and experimental observations, conductivity oscillations as a function of magnetic field with the magnetophonon resonances occurring at the phonon frequencies {ie1539-1} {ie1539-2}=cyclotron frequency). Divergences occurring in the magnetoconductivity near the magnetophonon resonances are removed by using the full resolvent operator in the tetradic self-energy operator of an electron. These additional terms provide necessary damping of the magnetophonon resonance oscillations. The present results are also shown to be qualitatively similar to those obtained by others using quantum Boltzmann's equation approach to quantum transport theory.