ISEE 1 and 2 observations of the high beta shock. [Terrestrial bow shock]
- Univ. of California, Los Angeles (United States)
- Los Alamos National Lab., NM (United States)
Measurements from the ISEE 1 and ISEE 2 spacecraft are used to examine the terrestrial bow shock under high beta conditions. On November 4, 1979, the large separation between the spacecraft, over 2,500 km along the shock normal, was such to allow simultaneous upstream and downstream measurements of the solar wind plasma for a period of about 8 min. These measurements are compared with and found to be in agreement with the predicted values of the Rankine-Hugoniot relations using the simple adiabatic approximation and a ratio of specific heats, [gamma], of 5/3. No additional terms, such as the heat flux, are needed to bring the measured and predicted values in agreement. Large magnetic field and density fluctuations were observed, but average downstream plasma conditions well away from the shock were relatively steady, near the predicted Rankine-Hugoniot values. The magnetic disturbances persisted well downstream and a hot, dense ion beam was detected leaking from the downstream region of the shock. Both of these phenomena can be attributed to the excitation of the Alfven ion cyclotron instability, which acts quickly to isotropize the ions close to the ramp of the shock. Additional shock crossings under high beta conditions having smaller separations allow the authors to confirm many of these observations.
- OSTI ID:
- 6787892
- Journal Information:
- Journal of Geophysical Research; (United States), Vol. 97:A12; ISSN 0148-0227
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
EARTH MAGNETOSPHERE
INTERACTIONS
SOLAR WIND
CYCLOTRON INSTABILITY
FLUCTUATIONS
MAGNETIC FIELDS
PLASMA
PLASMA DENSITY
RANKINE-HUGONIOT EQUATIONS
SHOCK WAVES
EARTH ATMOSPHERE
EQUATIONS
INSTABILITY
PLASMA INSTABILITY
PLASMA MICROINSTABILITIES
SOLAR ACTIVITY
VARIATIONS
661320* - Auroral
Ionospheric
& Magnetospheric Phenomena- (1992-)