Signature of a parallel electric field in ion and electron distributions in velocity space

Abstract

Charged particle data taken by the S3‐3 satellite, reported by Mizera and Fennell (1977), are presented as contours of the velocity distribution function on a velocity‐space diagram. This report focuses on the analytical technique used to interpret the particle data. Details of features exhibited by the electron and ion data in the velocity‐space representations are discussed in terms of a simple electrostatic acceleration model. The observed particle populations are separated in velocity‐space by recognizable demarcations calculated from the conservation laws in accordance with Liouville's theorem.

Observation of Field Aligned Ion and Electron Beams from SCATHA (P78-2).

“…We have shown that the ion beams observed by SCATHA are consistent with these beams coming from the auroral region, where they are interpreted as being formed by acceleration in a quasi-static electric field parallel to the magnetic field lines (Mizera and Fennell, 1977;Sharp et al, 1977;Croley et al, 1978) or by perpendicular heating at low altitudes and subsequent magnetic focusing as they move up the field lines (Sharp et al, 1977;Klumpar, 1979;Ungstrup et al, 1979;Comfort and Horwitz, 1980). scattering cannot be used to account for this discrepancy because the downflowing electron beams observed by Sharp et al, (1977) are just as narrow as the upgoing beams.…”

Energetic-Particle Populations and Cosmic-Ray Entry

“…The signature of an auroral electric field with a strong upward component parallel to B is evident in the high-resolution velocity-space distributions of ions and electrons compiled by CROLEY et al (1978). The results, presented in the form of contour plots on the (vu, v) plane, reveal clearly the boundaries in velocity space that separate adiabatically distinct classes of particles constrained to move along the same field line.…”

“…This is illustrated in Fig. 6, in which particle trajectories (as projected onto the equatorial as determined by CROLEY et al (1978). Hyperbola and ellipse demarcate regions of velocity space adiabatically accessible to the foot of the field line (100-km altitude) and the equator, respectively, in the presence of the parallel (to B) electric field that has been inferred from the S3-3 data for this time interval.…”

Recent advances in the study of electric and magnetic fields in the ionosphere and magnetosphere.

“…The question of the role of anomalous resistivity now becomes important in terms of an acceleration mechanism complementary to the electrostatic shock. CROLEY et al (1978) have also used S3-3 data to study the ion and electron distributions in velocity space and have been able to clearly distinguish between the background energetic particle distribution and that affected by the acceleration region using the conservation laws in accordance with Liouville's theorem as dealt with theoretically by CHID and SCHULZ (1978). Finally we note the results of three rocket flights reported by LYONS et al (1979) where it was reported that, over auroral forms, the net downward energy flux varies as V where V is the field-algined potential drop inferred from the monoenergetic peak in the observed spectra of the precipitating electrons.…”