Physics – Plasma Physics
Scientific paper
Dec 2009
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009agufmsh41b1676r&link_type=abstract
American Geophysical Union, Fall Meeting 2009, abstract #SH41B-1676
Physics
Plasma Physics
[2471] Ionosphere / Plasma Waves And Instabilities, [6984] Radio Science / Waves In Plasma, [7534] Solar Physics, Astrophysics, And Astronomy / Radio Emissions, [7847] Space Plasma Physics / Radiation Processes
Scientific paper
Linear mode conversion (LMC) of waves from one mode to another at constant frequency can occur in plasma irregularities because the natural modes in inhomogeneous plasmas need not be distinct but instead can be connected for restricted ranges of wave vectors k and frequencies f. Previous work suggests that the electrostatic (ES) Langmuir/z mode and free-space electromagnetic (EM) modes have two "radio windows", with multiple possible applications to solar radio bursts, planetary continuum radiation, auroral radio emissions, and ionospheric modification events. The first radio window is for Langmuir/z waves just above the local plasma frequency (fpe) with k almost aligned with the ambient magnetic field (B0) and the density gradient (▽N0). The second involves upper hybrid/z waves with f ~ fUH, the upper hybrid frequency, and k almost perpendicular to B0 and ▽N0. Here we use numerical simulations of the warm plasma fluid equations to investigate the detailed characteristics of LMC as functions of the outgoing EM o and x modes, k, the angles φ between B0 and ▽N0, B0, and the length scale of the density irregularity L. These results extend the recent demonstration that LMC produces both o and x-mode radiation when φ = 0, contrary to previous expectations that only the o mode is produced. Our new results include: (1) Only one radio window exists, smoothly linking the previous two windows as φ, f, and k change. (2) Both o and x-mode radiation are produced in the unmagnetized to moderately magnetized regimes, as found for the φ = 0 case. (3) Less than 10% of the incident ES energy is transformed into EM radiation. (4) In weakly magnetized situations almost equal amounts of o and x-mode radiation are produced, but only the o mode is produced for large enough B0. Applications of these results to natural solar and planetary emissions and to ionospheric modification experiments are also explored.
Cairns Iver H.
Kim Erik
Robinson Adam P.
No associations
LandOfFree
Electromagnetic radiation by linear mode conversion of Langmuir waves at oblique density inhomogeneities does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Electromagnetic radiation by linear mode conversion of Langmuir waves at oblique density inhomogeneities, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electromagnetic radiation by linear mode conversion of Langmuir waves at oblique density inhomogeneities will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1876880