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Generation of Alfven-ion cyclotron waves on auroral field lines in the presence of heavy ionsObservation of electromagnetic waves in the low-altitude auroral zone at frequencies between the proton and helium gyrofrequencies suggests that Alfven-ion cyclotron waves modified by the presence of helium ions are being excited. Estimates of the growth rates for this mode indicate that the auroral electron beam can provide the free energy for the instability. The effect of the heavy ions is to decrease the group velocity of the waves, leading to larger convective growth. Theoretical wave spectra are computed in the local approximation, which assumes that the gradient scale lengths in density and magnetic field are constant over the ray paths. Narrow banded spectral peaks similar to observations may be produced when the thickness of the electron beam is small (200 m at 3000 km altitude). Narrow beams also limit growth of whistler mode waves, which compete for the free energy of the electron beam.
Document ID
19830061977
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Lysak, R. L.
(Minnesota, University Minneapolis, MN, United States)
Temerin, M. A.
(California, University Berkeley, CA, United States)
Date Acquired
August 11, 2013
Publication Date
August 1, 1983
Publication Information
ISSN: 0094-8276
Subject Category
Geophysics
Accession Number
83A43195
Funding Number(s)
CONTRACT_GRANT: NAGW-75
CONTRACT_GRANT: NSF ATM-82-18128
CONTRACT_GRANT: N00014-81-C-0006
Distribution Limits
Public
Copyright
Other

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