Stimulated electromagnetic emission polarization under different polarizations of pump waves

Tereshchenko, E. D.; Yurik, R. Yu.; Baddeley, Lisa

doi:10.5194/angeo-33-295-2015

Cited by 1 publication

(1 citation statement)

References 14 publications

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“…The DM, 2DM, UM, and 2UM spectra have approximately 40% circularly polarization for time t < 85 s. The 2DM and 2UM appear to have a narrower spectral width of prominent circular polarization than that for DM and UM. The DM component polarization is preserved, which agrees with observations using the Space Plasma Exploration by Active Radar heating facility by (Tereshchenko et al, ).…”

Section: Experimental Results and Analysissupporting

confidence: 89%

Asymmetry in Stimulated Emission Polarization and Irregularity Evolution During Ionospheric Electron Gyroharmonic Heating

Scales

Bernhardt

et al. 2018

Geophysical Research Letters

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The first report is made of a holistic investigation of stimulated electromagnetic emission (SEE) during ionospheric electron gyroharmonic heating using a diagnostic approach at the High Frequency Active Auroral Research Program facility. The evolution of SEE polarization and plasma irregularity development near the third electron gyroharmonic 3f ce is investigated, which provides new insights into SEE generation mechanisms by the associated parametric decay instabilities. New more complex SEE spectral line behavior is clearly observed for varying transmitter beam angles. New SEE spectral emissions are observed at ∼75 kHz when pumping below 3f ce . The high-frequency radar echoes and SEE polarimetry appear asymmetric for pumping above 3f ce , which implies that the broad upshifted maximum spectral line formation involves plasma irregularities scattered by high-frequency radar echoes. This has important implications for understanding artificial ionization layer generation during ionospheric modification.Plain Language Summary Nonlinear interaction of high-power electromagnetic waves and magnetized plasmas produces a plethora of fundamental phenomena that can be exploited for powerful diagnostics of the Earth's ionospheric plasma. Stimulated electromagnetic emissions (SEEs) and plasma density turbulence, observable with high-frequency radars, arise from this nonlinear interaction as well as artificial ionization layers. The later has received considerable attention recently due to the importance of the associated fundamental physics and chemistry processes as well as the implications for modern communication and navigation systems. Artificial ionization layers are still not well understood, and this work seeks to provide insight into the generation mechanism by reporting the first results of a novel diagnostic approach that utilizes SEE and high-frequency radar measurements. The experiments were performed at the High Frequency Active Auroral Research Program facility. The evolution of SEE polarimetry and turbulent plasma density structures exhibits a prominent asymmetry when sweeping the transmitter frequency near electron gyrohamonic frequencies. A direct connection was observed between the plasma density structures and SEE spectral lines known to be associated with ionization layers. The observed asymmetric behavior therefore provides new insights into the linkage between ionization layers and generation of plasma density structures with specific characteristics. , S. J. (2018). Asymmetry in stimulated emission polarization and irregularity evolution during ionospheric electron gyroharmonic heating. Geophysical Research Letters, 45,[9363][9364][9365][9366][9367][9368][9369][9370][9371]

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Section: Experimental Results and Analysissupporting

confidence: 89%