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Parametric excitation of transverse waves in a plasma
Transverse electromagnetic wave propagation in cold plasma by external electric field oscillation
Invariant imbedding technique applied to the propagation of electromagnetic waves through inhomogeneous reentry plasmas
Invariant imbedding technique applied to electromagnetic wave propagation through inhomogeneous reentry plasmas
Electromagnetic wave propagation in a lossy plasma slab with a gradient transverse to the incident wave
Computer solution of plane electromagnetic wave interaction with bounded inhomogeneous plasma slab with electron density gradient transverse to wave
Nonlinear propagation of electromagnetic waves in a plasma containing random irregularities.
The problem of propagation of finite-amplitude electromagnetic waves in a plasma containing random irregularities is studied. Using a recently developed perturbation technique, a general equation for finite amplitude coherent waves is derived. Included in this equation are both the effects of quasi-harmonic nonlinear heating of electrons and random scattering by irregularities. The equation is solved in general by the equivalent linearization procedure. The amplitude of the coherent wave is found to be attenuated by collision and scattering. Both attenuation are affected by the nonlinear heating of the electrons. Curves showing the results for a specific example will be presented.
Computational study of nonlinear plasma waves. I - Simulation model and monochromatic wave propagation. II - Sideband instability and satellite growth
A hybrid plasma simulation model is described and applied to the study of electrostatic wave propagation in a one-dimensional Maxwellian plasma with periodic boundary conditions. The model employs a cloud-in-cell scheme which can drastically reduce the fluctuations in particle simulation models and greatly ease the computational difficulties of the Vlasov equation approach. A grid in velocity space is introduced and the particles are represented by points in the x-v phase space. The model is tested first in the absence of an applied signal and then in the presence of a small-amplitude perturbation. The method is also used to study propagation of an essentially monochromatic plane wave. Results on amplitude oscillation and nonlinear frequency shift are compared with available theories.
Hydromagnetic waves in a plasma with finite larmor radius.
Finite ion Larmor radius effect on MHD wave propagation in plasma
Plasma heating by anomalous dissipation of alfven waves propagating in inhomogeneous magnetic fields.
Viscous and ohmic dissipation of plasma alfven waves propagating in inhomogeneous magnetic fields
Radiation through plasma adjoining a conducting surface.
Wave propagation in inhomogeneous media next to conducting surface that contains radiating element
Propagation and wave guides filled with warm plasma
Propagation and plasma filled waveguides model derived by Boltzmann equation
Electromagnetic wave propagation in a magneto-plasma filled coaxial structure. I - Theoretical. II - Experimental
This study is concerned with the problem of electromagnetic wave propagation in a magneto-plasma filled coaxial structure. The problem is formulated using the classical boundary value problem approach. A numerical investigation shows the existence of propagating slow modes, backward modes, a quasi-TEM mode, and waveguide-type modes in a magneto-plasma filled coaxial structure. Dispersion curves for these different modes are presented. Measurements have been made of electromagnetic propagation in a coaxial electrode structure filled with longitudinally magnetized plasma. The annular plasma region had a 9.55 cm outer diameter, a 3.82 cm inner diameter and was approximately 60 cm long. A magnetic field of 300 gauss was employed. Electromagnetic wave frequencies were in the range .5 to 2.4 GHz. The plasma was generated by a continuous glow discharge. The resulting dispersion curves closely follow the predicted curves for the quasi-TEM mode.
MAVEN Observation of an Obliquely Propagating Low-Frequency Wave Upstream of Mars
We report Mars Atmosphere and Volatile EvolutioN (MAVEN) mission observations of a large amplitude low-frequency plasma wave that propagated oblique to the ambient magnetic field upstream of Mars along with a non-solar-wind plasma component that had a flow velocity perpendicular to the magnetic field. We consider nine possibilities for this wave that include various combinations of its propagation direction, polarization in the solar wind frame, and ion source responsible for its generation. Using the observed wave parameters and the measured plasma parameters as constraints, we uniquely identify the wave by systematically discarding these possibilities. We determine that the wave is a right-hand polarized wave that propagated upstream in the solar wind frame. We find two possibilities for the ion source that can be responsible for this wave generation. They are either newly born pickup protons or reflected solar wind protons from the bow shock.We determine that the observed non-solar-wind component is not responsible for the wave generation, and it is likely that the non-solar-wind component was merely perturbed by the passage of the wave.
Secular and nonsecular behavior for the cold plasma equations.
Higher order effects of electromagnetic wave, propagating in cold electron plasma
Evolution of Photon and Particle Spectra in Compact, Luminous Objects
Physical conditions in the radiating plasma in the cores of radio-strong quasars and active galactic nuclei cannot be derived from observations until the effects of relativistic aberration are understood. This requires determining both the bulk flow speeds and any wave or signal speed in the parsec-scale nuclear jets. In this project we studied several aspects of such waves. We considered constraints on jet deceleration by mass pickup, and found that bolometric luminosities of the active nuclei cannot constrain core jet speeds usefully. We also simulated observations of ballistic, helical trajectories and helical waves moving directly outwards along the jet. We found that ballistic trajectories are not allowed by the data; the helical features seen are very likely to be helical waves. We believe these are waves propagating in the jet plasma. To this end, we studied waves propagating in relativistic pair plasma jets. In particular, we undertook a program whose goal was to determine the nature of waves which can propagate in relativistic pair plasmas, and how such waves propagating in streaming jet plasma would be observed by an external observer. We developed the possibility of using pulsars as test cases for our models; this takes advantage of new technology in pulsar observations, and the similarity of the physical conditions in the pulsar magnetosphere to the dense, relativistic pair plasmas which exist in radio-strong quasars.
Coherent generation of the terrestrial kilometric radiation by nonlinear beatings between electrostatic waves
The propagation of electrostatic plasma waves in an inhomogeneous and magnetized plasma was studied. These waves, which are driven unstable by auroral beams of electrons, are shown to suffer a further geometrical amplification while they propagate towards resonances. Simultaneously, their group velocities tend to be aligned with the geomagnetic field. It is shown that the electrostatic energy tends to accumulate at, or near omega sub LH and omega sub UH, the local lower and upper hybrid frequencies. Due to this process, large amplitude electrostatic waves with very narrow spectra are observed near these frequencies at any place along the auroral field lines where intense beam driven instability takes place. These intense quasi-monochromatic electrostatic waves are shown to give rise to an intense electromagnetic radiation. Depending upon the ratio omega sub pe/omega sub ce between the electron plasma frequency and the electron gyro-frequency the electromagnetic wave can be radiated in the ordinary mode (at omega sub UH), or in the extraordinary (at 2 omega sub UH). As the ratio omega sub pe/omega sub ce tends to be rather small, it is shown that the most intense radiation should be boserved at 2 omega sub UH in the extraordinary mode.
Ionic Sound Waves in Plasmas Final Report
Acoustic apparatus for study of acoustic wave pressure-disturbance propagation in plasma
Alfven wave propagation in the Io plasma torus
Voyager 1 plasma measurements are combined with a model of Jupiter's magnetic field to calculate the time required for an Alfven wave to travel between Io and Jupiter's ionosphere, and the period of subsequent bounces between the northern and southern hemispheres of Io. The result is a wave pattern which extends around Jupiter as the multiply reflected Alfven waves are carried away from Io by the corotating magnetospheric plasma, exhibiting a general longitudinal structure which is independent of Io's position due to magnetic field geometry and Io torus plasma distribution. If the Alfven waves simulate decametric radio emission, the wave pattern predicts specific decametric emission properties for comparison with radio observation.
Transformation of the electric field at propagation of acoustic waves and their transition into plasma waves
Transformation of electric field at propagation of acoustic waves and their transition into plasma waves