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Titolo:
Charge neutrality and ion conic distributions at the equatorward electron edge of the midaltitude cusp
Autore:
Topliss, S; Johnstone, A; Coates, A; Peterson, WK; Kletzing, CA; Russell, CT;
Indirizzi:
Univ Coll London, Mullard Space Sci Lab, Dorking RH5 6NT, Surrey, England Univ Coll London Dorking Surrey England RH5 6NT RH5 6NT, Surrey, England Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA Univ Iowa Iowa City IA USA 52242 t Phys & Astron, Iowa City, IA 52242 USA Lockheed Martin Palo Alto Res Lab, Palo Alto, CA 94304 USA Lockheed MartinPalo Alto Res Lab Palo Alto CA USA 94304 to, CA 94304 USA Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90049 USA Univ Calif Los Angeles Los Angeles CA USA 90049 Los Angeles, CA 90049 USA
Titolo Testata:
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
fascicolo: A10, volume: 106, anno: 2001,
pagine: 21095 - 21108
SICI:
0148-0227(20011001)106:A10<21095:CNAICD>2.0.ZU;2-C
Fonte:
ISI
Lingua:
ENG
Soggetto:
CYCLOTRON WAVES; BOUNDARY-LAYER; HIGH-LATITUDE; FIELD LINES; POLAR CUSP; MAGNETOSPHERE; ENERGIZATION; ACCELERATION; ASSOCIATION; ALTITUDES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
36
Recensione:
Indirizzi per estratti:
Indirizzo: Topliss, S Univ Coll London, Mullard Space Sci Lab, Holmbury St Mary, Dorking RH5 6NT, Surrey, England Univ Coll London Holmbury St Mary Dorking Surrey England RH5 6NT
Citazione:
S. Topliss et al., "Charge neutrality and ion conic distributions at the equatorward electron edge of the midaltitude cusp", J GEO R-S P, 106(A10), 2001, pp. 21095-21108

Abstract

We have investigated the physical processes occurring in order to maintaincharge neutrality at the equatorward edge of the cusp by examining data from 200 Polar cusp crossings. The significant differences in magnetosheath ion and electron velocities could potentially create a region at the equatorward edge of the cusp where only solar wind electrons have access. Our calculations suggest that Polar should encounter this region at least 3 min before the first solar wind ions are observed. Only six Polar cusp crossings were identified, however, where a clear separate electron edge was observed. We then used state-of-the-art plasma instruments on Polar to examine particle features at the separate electron and ion edges. We find evidence that in the electron only region, electrons have been retarded by an electric potential above the spacecraft. We discuss the validity of examining electronspectra for evidence of retarding potentials, and we conclude that quantitative values cannot be obtained from single spacecraft measurements. We also fmd evidence of intermittent transverse ion acceleration in the electron only region. There are distinct differences in the ion conic distributions observed within the different regions at the equatorward edge of the cusp in terms of energy, pitch angle, and ion species. O+ conics are observed on closed field lines equatorward of the H+ cusp, while H+ and He conics are seen at higher latitudes. In the electron only region, and He+ conics have pitch angles between 90 degrees and 120 degrees. Further into the cusp, after the first solar wind ions are detected, higher-energy H+ and He+ conies with pitch angles extending to 180 degrees are measured. We suggest that processes occurring to maintain charge neutrality at the equatorward edge of the cusp may play a role in the generation of the ion conics observed.

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Documento generato il 09/12/19 alle ore 03:44:08