Full polarimetry measurements of stimulated electromagnetic emissions: First results

Citation
Td. Carozzi et al., Full polarimetry measurements of stimulated electromagnetic emissions: First results, J GEO R-S P, 106(A10), 2001, pp. 21395-21407
Citations number
17
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Space Sciences
Journal title
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
ISSN journal
2169-9380 → ACNP
Volume
106
Issue
A10
Year of publication
2001
Pages
21395 - 21407
Database
ISI
SICI code
0148-0227(20011001)106:A10<21395:FPMOSE>2.0.ZU;2-P
Abstract
A theory and technique for the measurement of the full state of polarizatio n (SOP) for wideband electromagnetic HF emissions from the ionosphere are i ntroduced. The technique was employed in a recent experiment at the Sura io nospheric HF pumping facility near Nizhniy Novgorod, Russia, to measure the full SOP of stimulated electromagnetic emissions (SEE) in their steady sta te. Measurements were made for O-mode polarized pump waves at two different frequencies: one below and one slightly above the fourth electron gyroharm onic frequency. The wideband spectral parameters measured in this experimen t include the horizontal intensity, the degree of horizontal circular polar ization, the degree of horizontal polarization and the tilt angle of the ho rizontal polarization ellipse. Evaluation of the data collected demonstrate s that the technique can be used for HF polarimetry and that, in particular , such measurements provide useful new diagnostics for SEE. Among the most important results regarding the polarimetry of SEE were low degrees of circ ular polarization in the frequency range between the peak of the broad upsh ifted maximum and the pump; some SEE features had degree of circularity and tilt angle values that were consistent with slightly oblique waves indicat ive of a distributed SEE source region; and the pump was found to have chan ged from an initial left-handed polarized state to a right-handed polarized state during steady state.