Effect Of Plasma Oscillations Research Articles

Restricted energy loss of ultrarelativistic particles in thin targets – A search for deviations from constancy

Abstract Experimental results for the restricted energy loss of ultrarelativistic electrons, with Lorentz factors up to 3 × 10 5 , in a 535 μ m thin silicon detector are presented. The combination of high Lorentz factors and thin targets, opens for the possibility to study two mutually excluding effects, both based upon theory and on scarce experimental observations. One is a disappearance of the density effect when the transit time becomes so short that the effect of plasma-oscillations becomes negligible. This would result in an increased energy loss as the Lorentz factor increases. The other is an effect based on the existence of a coherence length over which there are contributions to the energy loss. This effect leads to a substantially decreased energy loss for thin targets as the Lorentz factor increases. The latter is shown to be incompatible with our measurements, whereas the former may be present with a correction of a few percent to an otherwise constant energy loss. Furthermore, we point to significant effects related to synchrotron and transition radiation, that must be carefully considered in a possible future experiment, and may as well have been of significance for the conclusion in earlier experiments.

A theory of plasma oscillations in metallic nanoparticles

Equations describing the behavior of plasma oscillations that can arise on the surface as well as inside metallic spherical nanoparticles are obtained in the random-phase approximation. The frequencies of all characteristic plasma oscillations arising on the surface and in the volume of a particle are determined. It is shown that the volume plasma oscillations can give rise to forced oscillations on the surface of a nanoparticle. The effect of plasma oscillations on the optical properties of a dielectric medium containing metallic nanoparticles is determined.

A simplistic plasma dust removal model employing radiation pressure

A simple heuristic model is developed to examine the feasibility of using radiation pressure as a means to transport plasma dust out of the path of the forthcoming electron or photon beam. A slow electromagnetic surface wave coupled to a planar target or substrate exerts the required pressure in the removal process. The model is examined using data and parameters from single-shot radiography experiments. Optimal source requirements are identified for a typical radiography experiment. Source energies and powers are a minimum over an optimum band of frequencies where both conduction and plasma oscillation effects are mutually significant. Above the band of frequencies, dissipative losses in the surface supporting the surface wave increases exponentially with frequency. Below the optimal band, the energy concentration over the plume at the surface structure decreases significantly with frequency, thereby requiring higher source energies/powers for plasma removal.

The plasma spectrum effect on acoustic wave amplification by carrier drift in semiconductors

AbstractThe effect of plasma oscillations on acoustic wave amplification by carrier drift in semiconductors is discussed. A continuum theory is developed on the basis of hydrodynamical equations for the conduction electrons, the equations for the elastic vibrations of the crystal, and the Poisson equation. It is shown that if the plasma frequency ωp0 is much lower than the reciprocal value of the electron relaxation time for the scattering on phonons and impurities, τ−1, the results are in agreement with available calculations based on the equation for electrical conductivity and diffusion. However, in the case ωp0 τ ≫ 1 the amplification factor is multiplied by 2 ωpτ compared to the value predicted by those calculations, while the optimum drift velocity in this case is ωpτ times smaller.

Effect of plasma oscillations on electron density and temperature

Effect of plasma oscillations on electron density and temperature

A new approach to transport problems in fully ionized plasmas - II

A general method is given for solving the equations governing the propagation of one and two particles through a fully ionized, near-equilibrium plasma. The coefficient of electrical conductivity is determined variationally with the exclusion and inclusion of plasma oscillation effects. Without plasma oscillations the result agrees within about 3 per cent with the values of Cowling and of Spitzer and Harm. The effect of plasma oscillations is small, the correction being about 0.4 per cent.

A new approach to transport problems in fully ionized plasmas

Abstract Exact formulae for transport coefficients are given in terms of one and two-body equilibrium Green functions in velocity space. Equations are derived for these Green functions which apply under plasma conditions and which automatically include shielding and plasma oscillation effects. The method is illustrated by simple examples.