Initial thermal plasma observations from ISEE‐1

Baugher, Charles R.; Chappell, C. R.; Horwitz, J. L.; Shelley, E. G.; Young, D. T.

doi:10.1029/gl007i009p00657

Cited by 40 publications

(29 citation statements)

References 6 publications

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“…In this paper, the plasmapause location is identified from the thermal ion data as the transition from cold, rammed plasma to warm, anisotropic ion distributions. From previous reports [Baugher et al, 1980;Horwitz et al, 1981b], this transition appears to occur along the density gradient traditionally identified with the plasmapause and permits a more precise spatially resolved locator of the plasmapause. It is not certain, however, that this operational definition results in the same location as the conceptual definition above associated with the boundary of flux tube trajectories.…”

Section: Introductionmentioning

confidence: 58%

On the relationship of the plasmapause to the equatorward boundary of the auroral oval and to the inner edge of the plasma sheet

et al. 1982

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ISEE 1 observations of the plasmapause are compared with simultaneous observations of the electron plasma sheet and also the auroral oval observed in DMSP photographs. Only a limited amount of appropriate data was available for the comparisons: the plasmapause/plasma sheet inner edge comparisons were restricted to the early and late morning sectors, while there were two satisfactory comparisons of the plasmapause and the equatorward boundary of the auroral oval in the evening sector. However, these examples indicate that the plasmapause location often coincides to within ΔL ∼ 0.1–0.2 with both the plasma sheet inner boundary and the field line threading the equatorward boundary of the auroral oval. This co‐location of the plasmapause and the plasma sheet inner edge may be due to shielding of the magnetospheric convection electric field by an Alfvén layer located at the inner edge of the plasma sheet as discussed by Jaggi and Wolf (1973) and others.

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Section: Introductionmentioning

confidence: 58%

On the relationship of the plasmapause to the equatorward boundary of the auroral oval and to the inner edge of the plasma sheet

et al. 1982

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“…Its ionospheric source is implied by the presence of He + and O + observed with the mass spectrometers on ISEE 1 [Baugher et at., 1980] and GEOS .…”

Section: Introductionmentioning

confidence: 99%

Pancake pitch angle distributions in warm ions observed with ISEE 1

Horwitz¹,

Baugher²,

Chappell³

et al. 1981

J. Geophys. Res.

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Observations of pancake (peak flux near 90° pitch angle) distributions of low‐energy (≲100 eV) ions are reported. Pancake distributions occur often in H+ and He+ simultaneously while O+ fluxes are either undetectable or field‐aligned. These H+ and He+ pancake distributions typically display characteristic energies of the order of 10 eV and are frequently mixed with higher density, colder (κT≲3 eV), isotropic, quasi‐Maxwellian components. They appear often within the outer regions of the plasmasphere, and seem to occur most frequently on the dayside and near the magnetic equator.

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“…Satellite observations indicate that the ions in the magnetosphere of ionospheric origin are much more energetic than those in the ionosphere [Baugher et al, 1980;Horwitz and Chappell, 1979;Singh et al, 1982]. The energization of these ionospheric ions can be explained in terms of wave-particle interactions [Sharp et al, 1977;Ungstrup et al, 1979;Whalen et al, 1978;Klumpar, 1979;Papadopoulos et al, 1980;Singh et al, 1981;Chang and Coppi, 1981].…”

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confidence: 99%

Numerical calculations relevant to the initial expansion of the polar wind

Singh¹,

Schunk²

1982

J. Geophys. Res.

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The collisionless expansion of an H+‐O+ electron plasma into a vacuum was studied because of the relevance to the polar wind. A systematic parameter study was conducted by varying the ion composition, the initial ion‐electron temperature ratio, and the scale length of the density gradient at the plasma‐vacuum interface. The effect of gravity on O+ was also simulated. The character of the expansion is different depending on whether H+ is the major or minor ion. When H+ is the major ion, the density profile in the expansion region is always concave. On the other hand, when H+ is a minor ion, a distinct plateau forms in the H+ density, H+ drift velocity, and electrostatic potential profiles. The longer the density‐gradient scale length at the plasma‐vacuum interface, the longer it took for plateau formation. However, after plateau formation, the expansion proceeds nearly in an identical fashion regardless of the initial density‐gradient scale length. When O+ was fixed to simulate gravity, the lower end of the plateau region remained fixed at the location of the initial plasma‐vacuum interface, whereas when O+ was allowed to expand the H+ plateau region moved along with the moving O+ density front. For all cases, energetic H+ and O+ ions were observed in the expansion region. This suggests that the energization of ionospheric ions through the process of plasma expansion could be one of the mechanisms for creating the energetic ion population of ionospheric origin in the magnetosphere. Such a process would operate over the entire high‐latitude region, not just on auroral field lines. Since the largest density‐gradient scale length at the plasma‐vacuum interface that was considered is much less than typical ionospheric scale lengths, the numerical results cannot be directly applied to the polar wind. However, they illustrate the basic physical processes occuring in the polar wind expansion.

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Initial thermal plasma observations from ISEE‐1

Cited by 40 publications

References 6 publications

On the relationship of the plasmapause to the equatorward boundary of the auroral oval and to the inner edge of the plasma sheet

On the relationship of the plasmapause to the equatorward boundary of the auroral oval and to the inner edge of the plasma sheet

Pancake pitch angle distributions in warm ions observed with ISEE 1

Numerical calculations relevant to the initial expansion of the polar wind

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