AbstractA band of enhanced amplitudes which follows a local plasma frequency fn in raw high frequency (HF) noise spectra is usually related to plasma emissions in the upper hybrid band (fn, fu). The enhanced band in question occurs permanently in noise spectra recorded on the Intercosmos-19, APEX and CORONAS satellites in the altitude range of 500km–3000km. For moderately magnetized plasma with fn>2fc (fc – electron gyro frequency), the band occurs below fn determined from the topside sounder and impedance data or from electron beam induced spectra. The simulations of an equivalent circuit composed of a dipole antenna in a cold plasma and its preamplifiers, determined the physical origin of the band as the passive circuit resonance, due to inductive character of the antenna in a frequency band (fc, fu). The resonance spectral content is highly structured due to an inflight variability of the circuit impedances. In this report we analyze the noise and impedance spectra which are the most typical in an auroral zone if fn>fc. We focus attention on determination of local electron plasma density, essential for provisional HF mode classification. We found that the natural plasma emission in the upper hybrid band does not manifest itself as the banded natural emission, which may be used for reliable determination of local plasma frequency in the altitude range of 500–3000km. The fast magnetosonic mode predominates in the auroral emissions. The broadband and multi banded electromagnetic emissions extending from the fast magnetosonic band well above fn>fc are characteristic for the strong wave activity and are much less frequent.
An investigation of high frequency auroral plasma emissions with a tubular dipole antenna
Advances in Space Research ; 45 , 4 ; 553-575
2009-08-28
23 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
An investigation of high frequency auroral plasma emissions with a tubular dipole antenna
Online Contents | 2010
|Auroral planetary radio emissions, theoretical aspects
Elsevier | 1992
|Pattern Analysis of Airborne Dipole Antenna in High-Frequency Region
British Library Online Contents | 1997
|Waves in Space Plasma Dipole Antenna Subsystem
British Library Conference Proceedings | 1993
|Auroral Space Vehicle Charging Frequency
British Library Conference Proceedings | 1996
|