Heavy ions in the magnetosphere

Abstract

For purposes of this review heavy ions include all species of ions having a mass per unit charge of 2 AMU or greater. The discussion is limited primarily to ions in the energy range between 100 eV and 100 keV. Prior to the discovery in 1972 of large fluxes of energetic O + ions precipitating into the auroral Zone during geomagnetic storms, the only reported magnetosphere ion species observed in this energy range were helium and hydrogen. More recently O + and He + have been identified as significant components of the storm time ring current, suggesting that an ionosphere source may be involved in the generation of the fluxes responsible for this current. Mass spectrometer measurements on board the $3-3 satellite have shown that ionosphe,-ic ions in the auroral zone are frequently accelerated upward along geomagnetic field lines to several keV energy in the altitude region from 5000 km to greater than 8000 km. These observations also show evidence for acceleration perpendicular to the magnetic field and thus cannot be explained by a parallel electric field alone. This auroral acceleration region is most likely the source for the magnetospheric heavy ions of ionospheric origin, but further acceleration would probably be required to bring them to characteristic ring current energies. Recent observations from the GEOS-1 spacecraft combined with earlier results suggest comparable contributions to the hot magnetopheric plasma from the solar wind and the ionosphere.

Cluster observations of O+ escape in the magnetotail due to shock compression effects during the initial phase of the magnetic storm on 17 August 2001

“…The origin of plasma particles in the magnetotail was initially attributed only to the solar wind, but several observations have shown that ionospheric plasma is present in the magnetotail [e.g., Chappell et al, 1987]. In situ plasma and magnetic field observations showed that there is an O + and H + upward flow at high latitudes along magnetic field lines in the polar cusp/auroral oval region during substorms and storms [Shelley, 1979]. O + outflow has also been observed in the magnetotail [Candidi et al, 1982;Wilken et al, 1995;Zong et al, 1997Zong et al, , 1998Nishida, 2000;Korth et al, 2003;Ruan et al, 2005;Kistler et al, 2005].…”

The active magnetospheric particle tracer explorers (AMPTE) program

“…The discovery that a significant component of the near-Earth hot magnetospheric plasma was of ion ospheric origin [Shelley et al, 1972] further complicated the situation. Extensive plasma composition studies over the last decade have revealed that the relative contributions of the ionospheric and solar wind sources are ex tremely variable, and either can dominate at any given time [Shelley, 1979;Balsiger, 1982]. Because of the complexity of the natural sys tem, injection of artificial 'tracer' ions at a known location and time offers a promising tool for attacking the issues of plasma entry, acceleration, transport, and loss within the magnetosphere.…”

Energetic-Particle Populations and Cosmic-Ray Entry

“…SPJELDVIK (1979) has recently reviewed the subject from a more theoretical viewpoint, with emphasis on comparative charge-state abundances of heavier ions such as oxygen. PRANGS (1978), JOHNSON (1979), SHELLEY (1979), and HULTQVIST (1979) have reviewed past observations of energetic ions at altitudes <104km in the auroral regions and have thus emphasized ions of ionospheric origin. YOUNG (1979) has provided a review of these, as well as more recent observations, and has thus approached the subject from a magnetospheric perspective.…”