Inverse correlations between the ion temperature anisotropy and plasma beta in the Earth`s quasi-parallel magnetosheath

Journal Article · Mon Aug 01 04:00:00 EDT 1994 · Journal of Geophysical Research

DOI:https://doi.org/10.1029/94JA00865· OSTI ID:102610

Fuselier, S A ^[1]; Anderson, B J ^[2]; Gary, S P ^[3]

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1. Lockheed Palo Alto Research Lab., Palo Alto, CA (United States)
2. Johns Hopkins Univ., Laurel, MD (United States)
3. Los Alamos National Lab., NM (United States); and others

Average proton parameters in the magnetosheath downstream from the quasi-perpendicular shock (the quasi-perpendicular magnetosheath) for high solar wind dynamic pressure conditions are observed to vary continuously from high-beta, low-temperature anisotropy to low-beta, high-temperature anisotropy. Observations and theory have shown that this inverse correlation is a direct consequence of pitch angle scattering by electromagnetic ion cyclotron (EMIC) waves, which regulate the anisotropy, restoring the plasma toward marginal stability. Although the previously documented spectral characteristics of EMIC waves are not evident downstream of the quasi-parallel bow shock, the inverse anisotropy-beta relation found in the quasi-perpendicular magnetosheath also holds in the quasi-parallel magnetosheath. This indicates that the EMIC instability regulates the ion anisotropy regardless of the shock geometry. 23 refs., 4 figs.

• OSTI ID: 102610
• Journal Information: Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: A8 Vol. 99; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
BETA RATIO
CORRELATIONS
ION TEMPERATURE
MAGNETOSHEATH
SHOCK WAVES
SOLAR WIND