Sunlit cleft and polar cap ionospheric currents determined from rocket-borne magnetic field, plasma, and electric field observations
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Primdahl, F.↗
Engineering topics
Fahleson, U.
Publications and source records attributed to Fahleson, U..
Models for quasi-periodic electric fields and associated electron precipitation in the auroral zone
Quasi-periodic electric fields observed in the nighttime auroral oval and in the polar cleft had periods of between 0.5 and 3 s and amplitudes from 2 to 30 mV/m and exhibited left-hand and right-hand elliptical polarization. The events in the auroral oval were associated with substorms and visual auroral activity, and the spectral and polarization properties of the observed fields suggest that they represented the electric components of Pc 1 or Pi 1 micropulsations. One possibility is that the micropulsations result from Birkeland current chopping by an unstable double layer located at an altitude of approximately one earth radius. In this interpretation, the double layer is assumed to accelerate the observed electrons, the electron flux variations being due either to the inherent variations of the double layer or to its interaction with the micropulsations.
Petelski, E. F.↗
Rocket-borne wave, field, and plasma observations in unstable polar cap E-region
This paper presents initial results from the first comprehensively instrumented rocket flown through a Farley-unstable polar cap E-region. Ground-based ionosondes and magnetometers at two locations and HF radar backscatter at the launch site were used to determine the presence of a geographically widespread ionospheric plasma instability. The observed wave direction, electric field, and current density fit the predictions of the linear theory of the Farley instability, whereas the gradient-drift instability seems to be excluded by the geometry of the observations.
Olesen, J. K.↗
Rocket-borne particle, field, and plasma observations in the cleft region
Results are reported for comprehensive observations of magnetic and electric fields together with ambient and suprathermal plasmas above the dayside auroral oval with rocket-borne instrumentation which penetrated the cleft region. Measurements were also obtained equatorward and poleward of the cleft. Convection velocities as inferred from electric-field measurements were generally toward noon equatorward of the cleft and were antisunward over the polar cap. Observations of electron temperatures, electric fields, and low-frequency electrostatic noise provide strong evidence of a plasma instability (Farley-Buneman) in the E-layer associated with the appearance of the 'slant E condition' identified in ground-acquired ionograms. The positions of these measurements relative to that of the cleft were firmly established via the determination of the plasma environment with an electrostatic analyzer.
Ungstrup, E.↗
Electrodynamic sailing - Beating into the solar wind.
The recent suggestion by Alfven (1972) of a novel means of spacecraft propulsion based upon energy extraction from the electromagnetic field of the solar wind is critically reviewed. In response to this review, the original suggestion is somewhat amplified and clarified by its author.
Sonett, C. P.↗