Decay of electrostatic hydrogen cyclotron waves into ion acoustic modes on auroral field lines

Journal Article · Sun Mar 01 04:00:00 EST 1987 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA092iA03p02495· OSTI ID:5399062

Bergmann, R ^[1]; Hudson, M K ^[2]

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1. Rice Univ., Houston, TX (United States)
2. Dartmouth College, Hanover, NH (United States)

The coherent three-wave decay of a linearly unstable electrostatic hydrogen cyclotron (EHC) wave into stable EHC and ion acoustic modes is considered. Possible triads of parent and daughter waves are identified, and the coupling strength between the waves is calculated in two plasma models. The first model is the fluid limit of an electron-hydrogen plasma, and the second is a three-species kinetic model of the plasma in the evening auroral electron acceleration region. It is found that EHC waves commonly observed on auroral field lines are of sufficient amplitude to exceed the threshold for decay to weakly damped EHC modes. Further, frequency and wave number matching can be satisfied only if the acoustic mode is oblique to the geomagnetic field. This decay is proposed to be a saturation mechanism for the linearly unstable coherent EHC mode. The temporal dependence of the amplitudes of the three interacting modes, as predicted by the four coupled wave kinetic equations, indicates that the coherent decay can act to saturate the parent wave. Further, it indicates that observed EHC waves may actually be linearly marginally stable daughter EHC modes.

• OSTI ID: 5399062
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 92:A3; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ACCELERATION
AMPLITUDES
AURORAL ZONES
CYCLOTRON FREQUENCY
DECAY
ELECTRONS
ELEMENTARY PARTICLES
EQUATIONS
FERMIONS
GEOMAGNETIC FIELD
ION ACOUSTIC WAVES
ION WAVES
KINETIC EQUATIONS
LEPTONS
MAGNETIC FIELDS
PLASMA SIMULATION
PLASMA WAVES
SATURATION
SIMULATION