Drift mirror mode waves in the distant (X = 200 R/sub e/) magnetosheath

Journal Article · Mon Oct 01 00:00:00 EDT 1984 · Geophys. Res. Lett.; (United States)

DOI:https://doi.org/10.1029/GL011i010p01102· OSTI ID:5987975

Tsurutani, B T; Smith, E J; Richardson, I G; Lepping, R P; Jones, D E; Zwicki, R D; Bame, S J

Drift mirror waves have been detected 207 R/sub e/ downstream in the distant magnetosheath by instrumentation onboard ISEE-3. The MHD structures have estimated scale sizes of 4.6 x 10/sup 4/ to 2.3 x 10/sup 5/ km or 130 to 700 proton gyro-radii, assuming 1 keV protons. Simultaneous measurements on IMP-8 indicate that at the time of the events, the earth's magnetosphere was enveloped by a solar flare-associated interplanetary shock and driver gas. The (shocked) driver gas was characterized by an unusually low plasma density with a Beta (plasma pressure/magnetic pressure) of approx.0.2. From the instability criterion, ..beta../sub perpendicular//..beta../sub parallel/>1/..beta../sub perpendicular/, the magnetosheath plasma should not go mirror-mode unstable unless the anisotropy, ..beta../sub perpendicular// ..beta../sub 11/ is large, >6. These unusual conditions are met by the demonstrated presence of highly anisotropic, energetic 35--384 keV ions with P/sub perpendicular//P/sub 11/roughly-equal30. It is calculated that most of the plasma energy density can be due to >1 keV ions. The source of the ions is not well understood, but an appealing possibility is magnetic annihilation of the northward magnetosheath fields with southern hemisphere polar cusp magnetic fields.

• Research Organization: Jet Propulsion Laboratory, C.I.T., Pasadena, California 91109
• OSTI ID: 5987975
• Journal Information: Geophys. Res. Lett.; (United States), Vol. 11:10
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
MAGNETOSHEATH
HYDROMAGNETIC WAVES
ANISOTROPY
DRIFT INSTABILITY
EXPLORER SATELLITES
IMP SATELLITES
INTERPLANETARY MAGNETIC FIELDS
ION TEMPERATURE
PLASMA WAVES
INSTABILITY
MAGNETIC FIELDS
PLASMA INSTABILITY
PLASMA MICROINSTABILITIES
SATELLITES
640203* - Atmospheric Physics- Magnetospheric Phenomena- (-1987)