Several previous and new S3-3 satellite results on DC electric fields, field-aligned currents, and waves are described, interpreted theoretically, and applied to the understanding of auroral particle acceleration at altitudes below 8000 km. These results include the existence of two spatial scale sizes (less than 0.1 degree and a few degrees invariant latitude) in both the perpendicular and parallel electric fields; the predominance of S-shaped rather than V-shaped equipotential contours on both spatial saales; the correlated presence of field-aligned currents, low frequency wave turbulence, coherent ion cyclotron wave emissions and accelerated upmoving ions and downgoing electrons; intense waves inside electrostatic shocks and important wave-particle interactions therein; correlations of field-aligned currents with magnetospheric boundaries that are determined by convection electric field measurements; electron acceleration producing discrete auroral arcs in the smaller scale fields and producing inverted-V events in the larger scale fields; ion and electron acceleration due to both wave-particle interactions and the parallel electric fields. Further analyses of acceleration mechanisms and energetics are presented.

Satellite measurements and theories of low altitude auroral particle acceleration

The GEOS 1 and 2 spacecraft contain a set of particle and wave detectors which allow for a very comprehensive study of wave-particle interactions occurring within the equatorial region of the magnetosphere. This paper is devoted to interactions involving protons in the energy range 20 keV to 300 keV and ULF waves with frequencies below the proton gyrofrequency. It is shown that mose of the ion cyclotron waves (ICW's) detected in this frequency range have spectra whose charcteristic frequencies are organized in the vicinity of the He/sup +/ gyrofrequency. Simultaneous measurements of the ion composition in the thermal energy range (E< or approx. =110 eV) show these waves to be clearly associated with the abundance of cold He/sup +/ as well as the anisotropy of ions above 20 keV. The general characteristics of these helium-associated ULF events are presented in case studies of four events. The interpretation of this phenomenon is given in the present paper in terms of the propagation of ICW's in a He/sup +/ -rich plasma. It is shown that the shape of the cold plasma dispersion curve (for both parallel and non-parallel propgation) can adequately explain the main characteristics of the observed waves (frequency spectrum, polarization)more » as well as the differences between observations made onboard GEOS 1 and GEOS 2. The generation conditions of ion cylotron waves in such a multi-component plasma, as well as their quasi-linear effects on both the cold He/sup +/ ions and the hot protons, are discussed in a companion paper.« less

Wave‐particle interactions near ΩHe+ observed on GEOS 1 and 2 1. Propagation of ion cyclotron waves in He+‐rich plasma

Radio propagation modes in multicomponent plasma such as ionosphere, examing cutoff and crossover frequency resonances

Propagation in multicomponent plasmas

The polar-orbiting DE 1 spacecraft has provided the first measurements of high-latitude auroral phenomena. Three types of plasma-wave emissions were observed: auroral hiss, Z-mode radiation, and auroral kilometric radiation. Whistler mode auroral hiss emissions were observed on virtually every pass over the auroral zone. The shape of the auroral hiss frequency-time spectrum is explained by a whistler mode propagation effect if the radiation is emitted from a spatially localized source below the spacecraft. Broadband Z emissions have been observed in the low-density region over the auroral zone and polar cap. The auroral hiss may be distinguished from the Z-mode radiation by the sharp upper cutoff of the whistler mode at the local electron plasma frequency. Auroral kilometric radiation usually occurs at frequencies above electron gyrofrequency, indicating that this radiation is propagating in the free-space R-X mode.

Auroral hiss, Z-mode radiation and auroral kilometric radiation in the polar magnetosphere: DE-1 observations

Proton whistler /VLF phenomenon observed in satellite data/ discussing propagation in multicomponent plasma and ion cyclotron mode

Ion cyclotron whistlers

Barrington and Belrose1, Gurnett and O'Brien2 and Brice et al.3 have reported that very-low-frequency emissions at frequencies of a few kc/s may be observed in satellites immediately following an atmospheric which has propagated upwards to the satellite. Brice and Smith4 suggested that these triggered emissions were related to the lower hybrid resonance for propagation transverse to the Earth's magnetic field.

An ion gyrofrequency phenomenon observed in satellites.

AN interesting very low frequency (VLF) phenomenon which I shall call auroral V-emissions (AVEs) has been known for a number of years, although few reports have been published. The phenomenon has also been known informally as “short saucers” and “splashes”. The dynamic spectra of a collection of AVEs are shown in Fig. 1a. The AVEs shown here have a fairly low frequency minimum, near 0.5 kHz, and have time scales of the order of 10 s. The broader form at the upper part of the record may perhaps be an example of an AVE, but in this paper it will not be considered as an AVE. The name auroral V-emission is based on the region of observation and the V-shaped or hyperbolic spectral appearance. The hyperbolic shape is often quite symmetrical, particularly for the AVEs with shorter time scales. AVEs have only been observed in satellites, usually near the auroral zone. Noise bands with distinct intensity minima at harmonics of the local proton frequency are often observed at the centre of an AVE, especially for observations at relatively high altitude (3,000 km) and for AVEs with a low frequency minimum. The phenomena reported here have a much shorter time scale and a more well defined spectral appearance than the “V-type VLF hiss”1,2.

VLF observations of auroral beams as sources of a class of emissions

averaged 127, as against 150 for those of higher intelligence quotient, the finding is of limited significance. In this survey, however, on personality traits and sociometric status, the group of superior intelligence quotient were rated by their teachers higher than the more creative, which leads Vernon to stlggest that, in England and Wales, some of the more 'original' IS-yearolds may fail to find places at tUliversities because they were unpopular with their head teachers, and not good mixers. As C. Burt has pointed out, in the researches by Gi:ltzels and Jackson, correlations between separate tests for creativity were about on the same level as they were with intelligence tests, so that in these studies Vernon can find no evidence for a factor for creativity distinct from g and v. He doubts whether those for creativity cover more ground than the typical battery of tests for verbal intelligence, English and arithmetic already in presentday use. His main criticism, however, is that the tests which Getzel, Guilford and others have devised give no support to the assumption that they are valid for creativity in general: follow-up data are not available, and the gap between tests at about the time of entry to the secondary school and true creativity at the university is much too great. As indications of originality, Prof. Vernon holds that t ests like these scarcely go beyond empirical impressions 'which indicate that, in general, creative people tend to be

R. L. Smith

Papers

Ion cyclotron whistlers

An ion gyrofrequency phenomenon observed in satellites.

VLF observations of auroral beams as sources of a class of emissions

Recordings from Satellite Alouette I: Triggered Very-low-frequency Emissions

Recordings from Satellite Alouette I: A Very-low-frequency Plasma Resonance