Direct comparison of 1-m irregularity phase velocities and ion acoustic speeds in the auroral E region ionosphere

Journal Article · Thu Nov 01 00:00:00 EST 1990 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA095iA11p18989· OSTI ID:5102998

Haldoupis, C ^[1]; Schlegel, K ^[2]

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1. Univ. of Crete, Iraklion (Greece)
2. Max-Planck-Inst. fuer Aeronomie, Katlenburg-Lindau (West Germany)

Simultaneous coherent and incoherent scatter measurements from a common ionospheric volume are used to investigate the relationship between the phase velocity V{sub ph} of meter wavelength irregularities generated by the two-stream instability and the ambient ion acoustic speed C{sub s} in the auroral electrojet plasma, with the purpose of testing the widely accepted conviction that V{sub ph} is always limited at C{sub s}. Since it is not clear if the charged particles behave isothermally or adiabatically, the authors used several options for C{sub s} suggested in the literature, including (1) isothermal behavior for both ions and electrons, (2) isothermal ions and adiabatic electrons with 3 degrees of freedom, and (3) adiabatic electrons with 3 degrees of freedom and adiabatic ions with 1 degree of freedom. The comparison shows that option 3, in which {gamma}{sub e} = 5/3 and {gamma}{sub i} = 3, is rather unlikely. On the other hand, they find that option 2 ({gamma}{sub e} = 5/3, {gamma}{sub i} = 1) is more appropriate for use in the ion acoustic speed for meter wavelength waves. The analysis shows that on the average, phase velocities are limited to values which are {approximately} 15% higher than C{sub s} in line with the nonlinear kinetic model of the modified two-stream instability developed recently by Robinson and Honary (1990). Finally, in spite of the great deal of uncertainty involved in the V{sub ph} estimates, there is convincing evidence in the data showing that at times another mechanism, other than anomalous electron gas heating, is involved which allows for V{sub ph} to receive values well above C{sub s}.

• OSTI ID: 5102998
• Journal Information: Journal of Geophysical Research; (United States), Vol. 95:A11; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAL ZONES
RADIOWAVE RADIATION
E REGION
PHASE VELOCITY
BACKSCATTERING
COMPARATIVE EVALUATIONS
ELECTROJETS
ELECTRON DRIFT
ELECTRON TEMPERATURE
HEATING
ION DRIFT
MHZ RANGE
RADAR
TWO-STREAM INSTABILITY
CURRENTS
EARTH ATMOSPHERE
ELECTRIC CURRENTS
ELECTROMAGNETIC RADIATION
EVALUATION
FREQUENCY RANGE
INSTABILITY
IONOSPHERE
MEASURING INSTRUMENTS
PLANETARY IONOSPHERES
PLASMA INSTABILITY
PLASMA MICROINSTABILITIES
RADIATIONS
RANGE FINDERS
SCATTERING
VELOCITY
640201* - Atmospheric Physics- Auroral
Ionospheric
& Magetospheric Phenomena